varregion: refactor use of 'double heightmap[,]' into references to new class TerrainData

and push the implementation from Scene into the database readers and writers.

15 files changed, 1359 insertions, 325 deletions

diff --git a/OpenSim/Data/MSSQL/MSSQLSimulationData.cs b/OpenSim/Data/MSSQL/MSSQLSimulationData.cs
index 0d09be6..145b9c0 100644
--- a/OpenSim/Data/MSSQL/MSSQLSimulationData.cs
+++ b/OpenSim/Data/MSSQL/MSSQLSimulationData.cs
@@ -530,43 +530,52 @@ ELSE
         /// <returns></returns>
         public double[,] LoadTerrain(UUID regionID)
         {
-            double[,] terrain = new double[(int)Constants.RegionSize, (int)Constants.RegionSize];
-            terrain.Initialize();
+            double[,] ret = null;
+            TerrainData terrData = LoadTerrain(regionID, (int)Constants.RegionSize, (int)Constants.RegionSize, (int)Constants.RegionHeight);
+            if (terrData != null)
+                ret = terrData.GetDoubles();
+            return ret;
+        }
+
+        // Returns 'null' if region not found
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
+        {
+            TerrainData terrData = null;
 
             string sql = "select top 1 RegionUUID, Revision, Heightfield from terrain where RegionUUID = @RegionUUID order by Revision desc";
 
             using (SqlConnection conn = new SqlConnection(m_connectionString))
-            using (SqlCommand cmd = new SqlCommand(sql, conn))
             {
-                // MySqlParameter param = new MySqlParameter();
-                cmd.Parameters.Add(_Database.CreateParameter("@RegionUUID", regionID));
-                conn.Open();
-                using (SqlDataReader reader = cmd.ExecuteReader())
+                using (SqlCommand cmd = new SqlCommand(sql, conn))
                 {
-                    int rev;
-                    if (reader.Read())
+                    // MySqlParameter param = new MySqlParameter();
+                    cmd.Parameters.Add(_Database.CreateParameter("@RegionUUID", regionID));
+                    conn.Open();
+                    using (SqlDataReader reader = cmd.ExecuteReader())
                     {
-                        MemoryStream str = new MemoryStream((byte[])reader["Heightfield"]);
-                        BinaryReader br = new BinaryReader(str);
-                        for (int x = 0; x < (int)Constants.RegionSize; x++)
+                        if (reader.Read())
                         {
-                            for (int y = 0; y < (int)Constants.RegionSize; y++)
-                            {
-                                terrain[x, y] = br.ReadDouble();
-                            }
+                            int rev = (int)reader["Revision"];
+                            byte[] blob = (byte[])reader["Heightfield"];
+                            terrData = TerrainData.CreateFromDatabaseBlobFactory(pSizeX, pSizeY, pSizeZ, rev, blob);
                         }
-                        rev = (int)reader["Revision"];
-                    }
-                    else
-                    {
-                        _Log.Info("[REGION DB]: No terrain found for region");
-                        return null;
+                        else
+                        {
+                            _Log.Info("[REGION DB]: No terrain found for region");
+                            return null;
+                        }
+                        _Log.Info("[REGION DB]: Loaded terrain");
                     }
-                    _Log.Info("[REGION DB]: Loaded terrain revision r" + rev);
                 }
             }
 
-            return terrain;
+            return terrData;
+        }
+
+        // Legacy entry point for when terrain was always a 256x256 hieghtmap
+        public void StoreTerrain(double[,] ter, UUID regionID)
+        {
+            StoreTerrain(new HeightmapTerrainData(ter), regionID);
         }
 
         /// <summary>
@@ -574,10 +583,8 @@ ELSE
         /// </summary>
         /// <param name="terrain">terrain map data.</param>
         /// <param name="regionID">regionID.</param>
-        public void StoreTerrain(double[,] terrain, UUID regionID)
+        public void StoreTerrain(TerrainData terrData, UUID regionID)
         {
-            int revision = Util.UnixTimeSinceEpoch();
-
             //Delete old terrain map
             string sql = "delete from terrain where RegionUUID=@RegionUUID";
             using (SqlConnection conn = new SqlConnection(m_connectionString))
@@ -590,17 +597,23 @@ ELSE
 
             sql = "insert into terrain(RegionUUID, Revision, Heightfield) values(@RegionUUID, @Revision, @Heightfield)";
 
+            int terrainDBRevision;
+            Array terrainDBblob;
+            terrData.GetDatabaseBlob(out terrainDBRevision, out terrainDBblob);
+
             using (SqlConnection conn = new SqlConnection(m_connectionString))
-            using (SqlCommand cmd = new SqlCommand(sql, conn))
             {
-                cmd.Parameters.Add(_Database.CreateParameter("@RegionUUID", regionID));
-                cmd.Parameters.Add(_Database.CreateParameter("@Revision", revision));
-                cmd.Parameters.Add(_Database.CreateParameter("@Heightfield", serializeTerrain(terrain)));
-                conn.Open();
-                cmd.ExecuteNonQuery();
+                using (SqlCommand cmd = new SqlCommand(sql, conn))
+                {
+                    cmd.Parameters.Add(_Database.CreateParameter("@RegionUUID", regionID));
+                    cmd.Parameters.Add(_Database.CreateParameter("@Revision", terrainDBRevision));
+                    cmd.Parameters.Add(_Database.CreateParameter("@Heightfield", terrainDBblob));
+                    conn.Open();
+                    cmd.ExecuteNonQuery();
+                }
             }
 
-            _Log.Info("[REGION DB]: Stored terrain revision r " + revision);
+            _Log.Info("[REGION DB]: Stored terrain");
         }
 
         /// <summary>
@@ -1344,6 +1357,7 @@ VALUES
 
         #region Private Methods
 
+        /*
         /// <summary>
         /// Serializes the terrain data for storage in DB.
         /// </summary>
@@ -1367,6 +1381,7 @@ VALUES
 
             return str.ToArray();
         }
+        */
 
         /// <summary>
         /// Stores new regionsettings.
diff --git a/OpenSim/Data/MySQL/MySQLSimulationData.cs b/OpenSim/Data/MySQL/MySQLSimulationData.cs
index cc844ae..f910e44 100644
--- a/OpenSim/Data/MySQL/MySQLSimulationData.cs
+++ b/OpenSim/Data/MySQL/MySQLSimulationData.cs
@@ -48,8 +48,18 @@ namespace OpenSim.Data.MySQL
     public class MySQLSimulationData : ISimulationDataStore
     {
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+        private static string LogHeader = "[REGION DB MYSQL]";
 
         private string m_connectionString;
+
+        /// <summary>
+        /// This lock was being used to serialize database operations when the connection was shared, but this has
+        /// been unnecessary for a long time after we switched to using MySQL's underlying connection pooling instead.
+        /// FIXME: However, the locks remain in many places since they are effectively providing a level of 
+        /// transactionality.  This should be replaced by more efficient database transactions which would not require
+        /// unrelated operations to block each other or unrelated operations on the same tables from blocking each
+        /// other.
+        /// </summary>
         private object m_dbLock = new object();
 
         protected virtual Assembly Assembly
@@ -91,7 +101,7 @@ namespace OpenSim.Data.MySQL
             }
             catch (Exception e)
             {
-                m_log.Error("[REGION DB]: MySQL error in ExecuteReader: " + e.Message);
+                m_log.ErrorFormat("{0} MySQL error in ExecuteReader: {1}", LogHeader, e);
                 throw;
             }
 
@@ -574,12 +584,16 @@ namespace OpenSim.Data.MySQL
             }
         }
 
-        public virtual void StoreTerrain(double[,] ter, UUID regionID)
+        // Legacy entry point for when terrain was always a 256x256 hieghtmap
+        public void StoreTerrain(double[,] ter, UUID regionID)
+        {
+            StoreTerrain(new HeightmapTerrainData(ter), regionID);
+        }
+
+        public void StoreTerrain(TerrainData terrData, UUID regionID)
         {
             Util.FireAndForget(delegate(object x)
             {
-                double[,] oldTerrain = LoadTerrain(regionID);
-
                 m_log.Info("[REGION DB]: Storing terrain");
 
                 lock (m_dbLock)
@@ -601,8 +615,12 @@ namespace OpenSim.Data.MySQL
                                             "Revision, Heightfield) values (?RegionUUID, " +
                                             "1, ?Heightfield)";
 
-                                    cmd2.Parameters.AddWithValue("RegionUUID", regionID.ToString());
-                                    cmd2.Parameters.AddWithValue("Heightfield", SerializeTerrain(ter, oldTerrain));
+                                    int terrainDBRevision;
+                                    Array terrainDBblob;
+                                    terrData.GetDatabaseBlob(out terrainDBRevision, out terrainDBblob);
+
+                                    cmd2.Parameters.AddWithValue("Revision", terrainDBRevision);
+                                    cmd2.Parameters.AddWithValue("Heightfield", terrainDBblob);
 
                                     ExecuteNonQuery(cmd);
                                     ExecuteNonQuery(cmd2);
@@ -618,9 +636,20 @@ namespace OpenSim.Data.MySQL
             });
         }
 
+        // Legacy region loading
         public virtual double[,] LoadTerrain(UUID regionID)
         {
-            double[,] terrain = null;
+            double[,] ret = null;
+            TerrainData terrData = LoadTerrain(regionID, (int)Constants.RegionSize, (int)Constants.RegionSize, (int)Constants.RegionHeight);
+            if (terrData != null)
+                ret = terrData.GetDoubles();
+            return ret;
+        }
+
+        // Returns 'null' if region not found
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
+        {
+            TerrainData terrData = null;
 
             lock (m_dbLock)
             {
@@ -640,32 +669,15 @@ namespace OpenSim.Data.MySQL
                             while (reader.Read())
                             {
                                 int rev = Convert.ToInt32(reader["Revision"]);
-
-                                terrain = new double[(int)Constants.RegionSize, (int)Constants.RegionSize];
-                                terrain.Initialize();
-
-                                using (MemoryStream mstr = new MemoryStream((byte[])reader["Heightfield"]))
-                                {
-                                    using (BinaryReader br = new BinaryReader(mstr))
-                                    {
-                                        for (int x = 0; x < (int)Constants.RegionSize; x++)
-                                        {
-                                            for (int y = 0; y < (int)Constants.RegionSize; y++)
-                                            {
-                                                terrain[x, y] = br.ReadDouble();
-                                            }
-                                        }
-                                    }
-
-                                    m_log.InfoFormat("[REGION DB]: Loaded terrain revision r{0}", rev);
-                                }
+                                byte[] blob = (byte[])reader["Heightfield"];
+                                terrData = TerrainData.CreateFromDatabaseBlobFactory(pSizeX, pSizeY, pSizeZ, rev, blob);
                             }
                         }
                     }
                 }
             }
 
-            return terrain;
+            return terrData;
         }
 
         public virtual void RemoveLandObject(UUID globalID)
diff --git a/OpenSim/Data/Null/NullSimulationData.cs b/OpenSim/Data/Null/NullSimulationData.cs
index 15824a9..339e7f4 100644
--- a/OpenSim/Data/Null/NullSimulationData.cs
+++ b/OpenSim/Data/Null/NullSimulationData.cs
@@ -132,18 +132,36 @@ namespace OpenSim.Data.Null
             return new List<SceneObjectGroup>();
         }
 
-        Dictionary<UUID, double[,]> m_terrains = new Dictionary<UUID, double[,]>();
-        public void StoreTerrain(double[,] ter, UUID regionID)
+        Dictionary<UUID, TerrainData> m_terrains = new Dictionary<UUID, TerrainData>();
+        public void StoreTerrain(TerrainData ter, UUID regionID)
         {
             if (m_terrains.ContainsKey(regionID))
                 m_terrains.Remove(regionID);
             m_terrains.Add(regionID, ter);
         }
 
+        // Legacy. Just don't do this.
+        public void StoreTerrain(double[,] ter, UUID regionID)
+        {
+            TerrainData terrData = new HeightmapTerrainData(ter);
+            StoreTerrain(terrData, regionID);
+        }
+
+        // Legacy. Just don't do this.
+        // Returns 'null' if region not found
         public double[,] LoadTerrain(UUID regionID)
         {
             if (m_terrains.ContainsKey(regionID))
             {
+                return m_terrains[regionID].GetDoubles();
+            }
+            return null;
+        }
+
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
+        {
+            if (m_terrains.ContainsKey(regionID))
+            {
                 return m_terrains[regionID];
             }
             return null;
diff --git a/OpenSim/Data/PGSQL/PGSQLSimulationData.cs b/OpenSim/Data/PGSQL/PGSQLSimulationData.cs
index 3243635..cd02e05 100644
--- a/OpenSim/Data/PGSQL/PGSQLSimulationData.cs
+++ b/OpenSim/Data/PGSQL/PGSQLSimulationData.cs
@@ -46,6 +46,7 @@ namespace OpenSim.Data.PGSQL
     public class PGSQLSimulationData : ISimulationDataStore
     {
         private const string _migrationStore = "RegionStore";
+        private const string LogHeader = "[REGION DB PGSQL]";
 
         // private static FileSystemDataStore Instance = new FileSystemDataStore();
         private static readonly ILog _Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
@@ -523,8 +524,17 @@ namespace OpenSim.Data.PGSQL
         /// <returns></returns>
         public double[,] LoadTerrain(UUID regionID)
         {
-            double[,] terrain = new double[(int)Constants.RegionSize, (int)Constants.RegionSize];
-            terrain.Initialize();
+            double[,] ret = null;
+            TerrainData terrData = LoadTerrain(regionID, (int)Constants.RegionSize, (int)Constants.RegionSize, (int)Constants.RegionHeight);
+            if (terrData != null)
+                ret = terrData.GetDoubles();
+            return ret;
+        }
+
+        // Returns 'null' if region not found
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
+        {
+            TerrainData terrData = null;
 
             string sql = @"select ""RegionUUID"", ""Revision"", ""Heightfield"" from terrain 
                             where ""RegionUUID"" = :RegionUUID order by ""Revision"" desc limit 1; ";
@@ -540,16 +550,9 @@ namespace OpenSim.Data.PGSQL
                     int rev;
                     if (reader.Read())
                     {
-                        MemoryStream str = new MemoryStream((byte[])reader["Heightfield"]);
-                        BinaryReader br = new BinaryReader(str);
-                        for (int x = 0; x < (int)Constants.RegionSize; x++)
-                        {
-                            for (int y = 0; y < (int)Constants.RegionSize; y++)
-                            {
-                                terrain[x, y] = br.ReadDouble();
-                            }
-                        }
-                        rev = (int)reader["Revision"];
+                        rev = Convert.ToInt32(reader["Revision"]);
+                        byte[] blob = (byte[])reader["Heightfield"];
+                        terrData = TerrainData.CreateFromDatabaseBlobFactory(pSizeX, pSizeY, pSizeZ, rev, blob);
                     }
                     else
                     {
@@ -560,7 +563,13 @@ namespace OpenSim.Data.PGSQL
                 }
             }
 
-            return terrain;
+            return terrData;
+        }
+
+        // Legacy entry point for when terrain was always a 256x256 heightmap
+        public void StoreTerrain(double[,] terrain, UUID regionID)
+        {
+            StoreTerrain(new HeightmapTerrainData(terrain), regionID);
         }
 
         /// <summary>
@@ -568,35 +577,38 @@ namespace OpenSim.Data.PGSQL
         /// </summary>
         /// <param name="terrain">terrain map data.</param>
         /// <param name="regionID">regionID.</param>
-        public void StoreTerrain(double[,] terrain, UUID regionID)
+        public void StoreTerrain(TerrainData terrData, UUID regionID)
         {
-            int revision = Util.UnixTimeSinceEpoch();
-
             //Delete old terrain map
             string sql = @"delete from terrain where ""RegionUUID""=:RegionUUID";
             using (NpgsqlConnection conn = new NpgsqlConnection(m_connectionString))
-            using (NpgsqlCommand cmd = new NpgsqlCommand(sql, conn))
             {
-                cmd.Parameters.Add(_Database.CreateParameter("RegionUUID", regionID));
-                conn.Open();
-                cmd.ExecuteNonQuery();
+                using (NpgsqlCommand cmd = new NpgsqlCommand(sql, conn))
+                {
+                    cmd.Parameters.Add(_Database.CreateParameter("RegionUUID", regionID));
+                    conn.Open();
+                    cmd.ExecuteNonQuery();
+                }
             }
-
-            _Log.Info("[REGION DB]: Deleted terrain revision r " + revision);
+            int terrainDBRevision;
+            Array terrainDBblob;
+            terrData.GetDatabaseBlob(out terrainDBRevision, out terrainDBblob);
 
             sql = @"insert into terrain(""RegionUUID"", ""Revision"", ""Heightfield"") values(:RegionUUID, :Revision, :Heightfield)";
 
             using (NpgsqlConnection conn = new NpgsqlConnection(m_connectionString))
-            using (NpgsqlCommand cmd = new NpgsqlCommand(sql, conn))
             {
-                cmd.Parameters.Add(_Database.CreateParameter("RegionUUID", regionID));
-                cmd.Parameters.Add(_Database.CreateParameter("Revision", revision));
-                cmd.Parameters.Add(_Database.CreateParameter("Heightfield", serializeTerrain(terrain)));
-                conn.Open();
-                cmd.ExecuteNonQuery();
+                using (NpgsqlCommand cmd = new NpgsqlCommand(sql, conn))
+                {
+                    cmd.Parameters.Add(_Database.CreateParameter("RegionUUID", regionID));
+                    cmd.Parameters.Add(_Database.CreateParameter("Revision", terrainDBRevision));
+                    cmd.Parameters.Add(_Database.CreateParameter("Heightfield", terrainDBblob));
+                    conn.Open();
+                    cmd.ExecuteNonQuery();
+                }
             }
 
-            _Log.Info("[REGION DB]: Stored terrain revision r " + revision);
+            _Log.Info("[REGION DB]: Stored terrain revision r " + terrainDBRevision);
         }
 
         /// <summary>
@@ -1349,6 +1361,7 @@ namespace OpenSim.Data.PGSQL
 
         #region Private Methods
 
+        /*
         /// <summary>
         /// Serializes the terrain data for storage in DB.
         /// </summary>
@@ -1372,6 +1385,7 @@ namespace OpenSim.Data.PGSQL
 
             return str.ToArray();
         }
+        */
 
         /// <summary>
         /// Stores new regionsettings.
diff --git a/OpenSim/Data/SQLite/SQLiteSimulationData.cs b/OpenSim/Data/SQLite/SQLiteSimulationData.cs
index 4d6a80a..d28c227 100644
--- a/OpenSim/Data/SQLite/SQLiteSimulationData.cs
+++ b/OpenSim/Data/SQLite/SQLiteSimulationData.cs
@@ -51,6 +51,7 @@ namespace OpenSim.Data.SQLite
     public class SQLiteSimulationData : ISimulationDataStore
     {
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+        private static readonly string LogHeader = "[REGION DB SQLLITE]";
 
         private const string primSelect = "select * from prims";
         private const string shapeSelect = "select * from primshapes";
@@ -819,12 +820,18 @@ namespace OpenSim.Data.SQLite
             prim.Inventory.RestoreInventoryItems(inventory);
         }
 
+        // Legacy entry point for when terrain was always a 256x256 hieghtmap
+        public void StoreTerrain(double[,] ter, UUID regionID)
+        {
+            StoreTerrain(new HeightmapTerrainData(ter), regionID);
+        }
+
         /// <summary>
         /// Store a terrain revision in region storage
         /// </summary>
         /// <param name="ter">terrain heightfield</param>
         /// <param name="regionID">region UUID</param>
-        public void StoreTerrain(double[,] ter, UUID regionID)
+        public void StoreTerrain(TerrainData terrData, UUID regionID)
         {
             lock (ds)
             {
@@ -853,11 +860,17 @@ namespace OpenSim.Data.SQLite
                 String sql = "insert into terrain(RegionUUID, Revision, Heightfield)" +
                              " values(:RegionUUID, :Revision, :Heightfield)";
 
+                int terrainDBRevision;
+                Array terrainDBblob;
+                terrData.GetDatabaseBlob(out terrainDBRevision, out terrainDBblob);
+
+                m_log.DebugFormat("{0} Storing terrain revision r {1}", LogHeader, terrainDBRevision);
+
                 using (SqliteCommand cmd = new SqliteCommand(sql, m_conn))
                 {
                     cmd.Parameters.Add(new SqliteParameter(":RegionUUID", regionID.ToString()));
-                    cmd.Parameters.Add(new SqliteParameter(":Revision", revision));
-                    cmd.Parameters.Add(new SqliteParameter(":Heightfield", serializeTerrain(ter)));
+                    cmd.Parameters.Add(new SqliteParameter(":Revision", terrainDBRevision));
+                    cmd.Parameters.Add(new SqliteParameter(":Heightfield", terrainDBblob));
                     cmd.ExecuteNonQuery();
                 }
             }
@@ -870,11 +883,20 @@ namespace OpenSim.Data.SQLite
         /// <returns>Heightfield data</returns>
         public double[,] LoadTerrain(UUID regionID)
         {
+            double[,] ret = null;
+            TerrainData terrData = LoadTerrain(regionID, (int)Constants.RegionSize, (int)Constants.RegionSize, (int)Constants.RegionHeight);
+            if (terrData != null)
+                ret = terrData.GetDoubles();
+            return ret;
+        }
+
+        // Returns 'null' if region not found
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
+        {
+            TerrainData terrData = null;
+
             lock (ds)
             {
-                double[,] terret = new double[(int)Constants.RegionSize, (int)Constants.RegionSize];
-                terret.Initialize();
-
                 String sql = "select RegionUUID, Revision, Heightfield from terrain" +
                              " where RegionUUID=:RegionUUID order by Revision desc";
 
@@ -887,21 +909,9 @@ namespace OpenSim.Data.SQLite
                         int rev = 0;
                         if (row.Read())
                         {
-                            // TODO: put this into a function
-                            using (MemoryStream str = new MemoryStream((byte[])row["Heightfield"]))
-                            {
-                                using (BinaryReader br = new BinaryReader(str))
-                                {
-                                    for (int x = 0; x < (int)Constants.RegionSize; x++)
-                                    {
-                                        for (int y = 0; y < (int)Constants.RegionSize; y++)
-                                        {
-                                            terret[x, y] = br.ReadDouble();
-                                        }
-                                    }
-                                }
-                            }
                             rev = Convert.ToInt32(row["Revision"]);
+                            byte[] blob = (byte[])row["Heightfield"];
+                            terrData = TerrainData.CreateFromDatabaseBlobFactory(pSizeX, pSizeY, pSizeZ, rev, blob);
                         }
                         else
                         {
@@ -912,8 +922,8 @@ namespace OpenSim.Data.SQLite
                         m_log.Debug("[SQLITE REGION DB]: Loaded terrain revision r" + rev.ToString());
                     }
                 }
-                return terret;
             }
+            return terrData;
         }
 
         public void RemoveLandObject(UUID globalID)
@@ -2016,6 +2026,7 @@ namespace OpenSim.Data.SQLite
             return entry;
         }
 
+        /*
         /// <summary>
         ///
         /// </summary>
@@ -2033,6 +2044,7 @@ namespace OpenSim.Data.SQLite
 
             return str.ToArray();
         }
+        */
 
         //         private void fillTerrainRow(DataRow row, UUID regionUUID, int rev, double[,] val)
         //         {
diff --git a/OpenSim/Framework/TerrainData.cs b/OpenSim/Framework/TerrainData.cs
new file mode 100644
index 0000000..6b1be4e
--- /dev/null
+++ b/OpenSim/Framework/TerrainData.cs
@@ -0,0 +1,464 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+
+using OpenMetaverse;
+
+using log4net;
+
+namespace OpenSim.Framework
+{
+    public abstract class TerrainData
+    {
+        // Terrain always is a square
+        public int SizeX { get; protected set; }
+        public int SizeY { get; protected set; }
+        public int SizeZ { get; protected set; }
+
+        // A height used when the user doesn't specify anything
+        public const float DefaultTerrainHeight = 21f;
+
+        public abstract float this[int x, int y] { get; set; }
+        // Someday terrain will have caves
+        public abstract float this[int x, int y, int z] { get; set; }
+
+        public abstract bool IsTaintedAt(int xx, int yy);
+        public abstract bool IsTaintedAt(int xx, int yy, bool clearOnTest);
+        public abstract void TaintAllTerrain();
+        public abstract void ClearTaint();
+
+        public abstract void ClearLand();
+        public abstract void ClearLand(float height);
+
+        // Return a representation of this terrain for storing as a blob in the database.
+        // Returns 'true' to say blob was stored in the 'out' locations.
+        public abstract bool GetDatabaseBlob(out int DBFormatRevisionCode, out Array blob);
+
+        // Given a revision code and a blob from the database, create and return the right type of TerrainData.
+        // The sizes passed are the expected size of the region. The database info will be used to
+        //     initialize the heightmap of that sized region with as much data is in the blob.
+        // Return created TerrainData or 'null' if unsuccessful.
+        public static TerrainData CreateFromDatabaseBlobFactory(int pSizeX, int pSizeY, int pSizeZ, int pFormatCode, byte[] pBlob)
+        {
+            // For the moment, there is only one implementation class
+            return new HeightmapTerrainData(pSizeX, pSizeY, pSizeZ, pFormatCode, pBlob);
+        }
+
+        // return a special compressed representation of the heightmap in ints
+        public abstract int[] GetCompressedMap();
+        public abstract float CompressionFactor { get; }
+
+        public abstract float[] GetFloatsSerialized();
+        public abstract double[,] GetDoubles();
+        public abstract TerrainData Clone();
+    }
+
+    // The terrain is stored in the database as a blob with a 'revision' field.
+    // Some implementations of terrain storage would fill the revision field with
+    //    the time the terrain was stored. When real revisions were added and this
+    //    feature removed, that left some old entries with the time in the revision
+    //    field.
+    // Thus, if revision is greater than 'RevisionHigh' then terrain db entry is
+    //    left over and it is presumed to be 'Legacy256'.
+    // Numbers are arbitrary and are chosen to to reduce possible mis-interpretation.
+    // If a revision does not match any of these, it is assumed to be Legacy256.
+    public enum DBTerrainRevision
+    {
+        // Terrain is 'double[256,256]'
+        Legacy256 = 11,
+        // Terrain is 'int32, int32, float[,]' where the ints are X and Y dimensions
+        // The dimensions are presumed to be multiples of 16 and, more likely, multiples of 256.
+        Variable2D = 22,
+        // Terrain is 'int32, int32, int32, int16[]' where the ints are X and Y dimensions
+        //   and third int is the 'compression factor'. The heights are compressed as
+        //   "int compressedHeight = (int)(height * compressionFactor);"
+        // The dimensions are presumed to be multiples of 16 and, more likely, multiples of 256.
+        Compressed2D = 27,
+        // A revision that is not listed above or any revision greater than this value is 'Legacy256'.
+        RevisionHigh = 1234
+    }
+
+    // Version of terrain that is a heightmap.
+    // This should really be 'LLOptimizedHeightmapTerrainData' as it includes knowledge
+    //    of 'patches' which are 16x16 terrain areas which can be sent separately to the viewer.
+    // The heighmap is kept as an array of integers. The integer values are converted to
+    //    and from floats by TerrainCompressionFactor.
+    public class HeightmapTerrainData : TerrainData
+    {
+        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+        private static string LogHeader = "[HEIGHTMAP TERRAIN DATA]";
+
+        // TerrainData.this[x, y]
+        public override float this[int x, int y]
+        {
+            get { return FromCompressedHeight(m_heightmap[x, y]); }
+            set {
+                int newVal = ToCompressedHeight(value);
+                if (m_heightmap[x, y] != newVal)
+                {
+                    m_heightmap[x, y] = newVal;
+                    m_taint[x / Constants.TerrainPatchSize, y / Constants.TerrainPatchSize] = true;
+                }
+            }
+        }
+
+        // TerrainData.this[x, y, z]
+        public override float this[int x, int y, int z]
+        {
+            get { return this[x, y]; }
+            set { this[x, y] = value; }
+        }
+
+        // TerrainData.ClearTaint
+        public override void ClearTaint()
+        {
+            SetAllTaint(false);
+        }
+
+        // TerrainData.TaintAllTerrain
+        public override void TaintAllTerrain()
+        {
+            SetAllTaint(true);
+        }
+
+        private void SetAllTaint(bool setting)
+        {
+            for (int ii = 0; ii < m_taint.GetLength(0); ii++)
+                for (int jj = 0; jj < m_taint.GetLength(1); jj++)
+                    m_taint[ii, jj] = setting;
+        }
+
+        // TerrainData.ClearLand
+        public override void ClearLand()
+        {
+            ClearLand(DefaultTerrainHeight);
+        }
+        // TerrainData.ClearLand(float)
+        public override void ClearLand(float pHeight)
+        {
+            int flatHeight = ToCompressedHeight(pHeight);
+            for (int xx = 0; xx < SizeX; xx++)
+                for (int yy = 0; yy < SizeY; yy++)
+                    m_heightmap[xx, yy] = flatHeight;
+        }
+
+        // Return 'true' of the patch that contains these region coordinates has been modified.
+        // Note that checking the taint clears it.
+        // There is existing code that relies on this feature.
+        public override bool IsTaintedAt(int xx, int yy, bool clearOnTest)
+        {
+            int tx = xx / Constants.TerrainPatchSize;
+            int ty = yy / Constants.TerrainPatchSize;
+            bool ret =  m_taint[tx, ty];
+            if (ret && clearOnTest)
+                m_taint[tx, ty] = false;
+            return ret;
+        }
+
+        // Old form that clears the taint flag when we check it.
+        public override bool IsTaintedAt(int xx, int yy)
+        {
+            return IsTaintedAt(xx, yy, true /* clearOnTest */);
+        }
+
+        // TerrainData.GetDatabaseBlob
+        // The user wants something to store in the database.
+        public override bool GetDatabaseBlob(out int DBRevisionCode, out Array blob)
+        {
+            bool ret = false;
+            if (SizeX == Constants.RegionSize && SizeY == Constants.RegionSize)
+            {
+                DBRevisionCode = (int)DBTerrainRevision.Legacy256;
+                blob = ToLegacyTerrainSerialization();
+                ret = true;
+            }
+            else
+            {
+                DBRevisionCode = (int)DBTerrainRevision.Compressed2D;
+                blob = ToCompressedTerrainSerialization();
+                ret = true;
+            }
+            return ret;
+        }
+
+        // TerrainData.CompressionFactor
+        private float m_compressionFactor = 100.0f;
+        public override float CompressionFactor { get { return m_compressionFactor; } }
+
+        // TerrainData.GetCompressedMap
+        public override int[] GetCompressedMap()
+        {
+            int[] newMap = new int[SizeX * SizeY];
+
+            int ind = 0;
+            for (int xx = 0; xx < SizeX; xx++)
+                for (int yy = 0; yy < SizeY; yy++)
+                    newMap[ind++] = m_heightmap[xx, yy];
+
+            return newMap;
+
+        }
+        // TerrainData.Clone
+        public override TerrainData Clone()
+        {
+            HeightmapTerrainData ret = new HeightmapTerrainData(SizeX, SizeY, SizeZ);
+            ret.m_heightmap = (int[,])this.m_heightmap.Clone();
+            return ret;
+        }
+
+        // TerrainData.GetFloatsSerialized
+        // This one dimensional version is ordered so height = map[y*sizeX+x];
+        // DEPRECATED: don't use this function as it does not retain the dimensions of the terrain
+        //     and the caller will probably do the wrong thing if the terrain is not the legacy 256x256.
+        public override float[] GetFloatsSerialized()
+        {
+            int points = SizeX * SizeY;
+            float[] heights = new float[points];
+
+            int idx = 0;
+            for (int jj = 0; jj < SizeY; jj++)
+                for (int ii = 0; ii < SizeX; ii++)
+                {
+                    heights[idx++] = FromCompressedHeight(m_heightmap[ii, jj]);
+                }
+
+            return heights;
+        }
+
+        // TerrainData.GetDoubles
+        public override double[,] GetDoubles()
+        {
+            double[,] ret = new double[SizeX, SizeY];
+            for (int xx = 0; xx < SizeX; xx++)
+                for (int yy = 0; yy < SizeY; yy++)
+                    ret[xx, yy] = FromCompressedHeight(m_heightmap[xx, yy]);
+
+            return ret;
+        }
+
+
+        // =============================================================
+
+        private int[,] m_heightmap;
+        // Remember subregions of the heightmap that has changed.
+        private bool[,] m_taint;
+
+        // To save space (especially for large regions), keep the height as a short integer
+        //    that is coded as the float height times the compression factor (usually '100'
+        //    to make for two decimal points).
+        public int ToCompressedHeight(double pHeight)
+        {
+            return (int)(pHeight * CompressionFactor);
+        }
+
+        public float FromCompressedHeight(int pHeight)
+        {
+            return ((float)pHeight) / CompressionFactor;
+        }
+
+        // To keep with the legacy theme, create an instance of this class based on the
+        //     way terrain used to be passed around.
+        public HeightmapTerrainData(double[,] pTerrain)
+        {
+            SizeX = pTerrain.GetLength(0);
+            SizeY = pTerrain.GetLength(1);
+            SizeZ = (int)Constants.RegionHeight;
+            m_compressionFactor = 100.0f;
+
+            m_heightmap = new int[SizeX, SizeY];
+            for (int ii = 0; ii < SizeX; ii++)
+            {
+                for (int jj = 0; jj < SizeY; jj++)
+                {
+                    m_heightmap[ii, jj] = ToCompressedHeight(pTerrain[ii, jj]);
+
+                }
+            }
+            // m_log.DebugFormat("{0} new by doubles. sizeX={1}, sizeY={2}, sizeZ={3}", LogHeader, SizeX, SizeY, SizeZ);
+
+            m_taint = new bool[SizeX / Constants.TerrainPatchSize, SizeY / Constants.TerrainPatchSize];
+            ClearTaint();
+        }
+
+        // Create underlying structures but don't initialize the heightmap assuming the caller will immediately do that
+        public HeightmapTerrainData(int pX, int pY, int pZ)
+        {
+            SizeX = pX;
+            SizeY = pY;
+            SizeZ = pZ;
+            m_compressionFactor = 100.0f;
+            m_heightmap = new int[SizeX, SizeY];
+            m_taint = new bool[SizeX / Constants.TerrainPatchSize, SizeY / Constants.TerrainPatchSize];
+            // m_log.DebugFormat("{0} new by dimensions. sizeX={1}, sizeY={2}, sizeZ={3}", LogHeader, SizeX, SizeY, SizeZ);
+            ClearTaint();
+            ClearLand(0f);
+        }
+
+        public HeightmapTerrainData(int[] cmap, float pCompressionFactor, int pX, int pY, int pZ) : this(pX, pY, pZ)
+        {
+            m_compressionFactor = pCompressionFactor;
+            int ind = 0;
+            for (int xx = 0; xx < SizeX; xx++)
+                for (int yy = 0; yy < SizeY; yy++)
+                    m_heightmap[xx, yy] = cmap[ind++];
+            // m_log.DebugFormat("{0} new by compressed map. sizeX={1}, sizeY={2}, sizeZ={3}", LogHeader, SizeX, SizeY, SizeZ);
+        }
+
+        // Create a heighmap from a database blob
+        public HeightmapTerrainData(int pSizeX, int pSizeY, int pSizeZ, int pFormatCode, byte[] pBlob) : this(pSizeX, pSizeY, pSizeZ)
+        {
+            switch ((DBTerrainRevision)pFormatCode)
+            {
+                case DBTerrainRevision.Compressed2D:
+                    FromCompressedTerrainSerialization(pBlob);
+                    m_log.DebugFormat("{0} HeightmapTerrainData create from Compressed2D serialization. Size=<{1},{2}>", LogHeader, SizeX, SizeY);
+                    break;
+                default:
+                    FromLegacyTerrainSerialization(pBlob);
+                    m_log.DebugFormat("{0} HeightmapTerrainData create from legacy serialization. Size=<{1},{2}>", LogHeader, SizeX, SizeY);
+                    break;
+            }
+        }
+
+        // Just create an array of doubles. Presumes the caller implicitly knows the size.
+        public Array ToLegacyTerrainSerialization()
+        {
+            Array ret = null;
+
+            using (MemoryStream str = new MemoryStream((int)Constants.RegionSize * (int)Constants.RegionSize * sizeof(double)))
+            {
+                using (BinaryWriter bw = new BinaryWriter(str))
+                {
+                    for (int xx = 0; xx < Constants.RegionSize; xx++)
+                    {
+                        for (int yy = 0; yy < Constants.RegionSize; yy++)
+                        {
+                            double height = this[xx, yy];
+                            if (height == 0.0)
+                                height = double.Epsilon;
+                            bw.Write(height);
+                        }
+                    }
+                }
+                ret = str.ToArray();
+            }
+            return ret;
+        }
+
+        // Just create an array of doubles. Presumes the caller implicitly knows the size.
+        public void FromLegacyTerrainSerialization(byte[] pBlob)
+        {
+            // In case database info doesn't match real terrain size, initialize the whole terrain.
+            ClearLand();
+
+            using (MemoryStream mstr = new MemoryStream(pBlob))
+            {
+                using (BinaryReader br = new BinaryReader(mstr))
+                {
+                    for (int xx = 0; xx < (int)Constants.RegionSize; xx++)
+                    {
+                        for (int yy = 0; yy < (int)Constants.RegionSize; yy++)
+                        {
+                            float val = (float)br.ReadDouble();
+                            if (xx < SizeX && yy < SizeY)
+                                m_heightmap[xx, yy] = ToCompressedHeight(val);
+                        }
+                    }
+                }
+                ClearTaint();
+            }
+        }
+        
+        // See the reader below.
+        public Array ToCompressedTerrainSerialization()
+        {
+            Array ret = null;
+            using (MemoryStream str = new MemoryStream((3 * sizeof(Int32)) + (SizeX * SizeY * sizeof(Int16))))
+            {
+                using (BinaryWriter bw = new BinaryWriter(str))
+                {
+                    bw.Write((Int32)DBTerrainRevision.Compressed2D);
+                    bw.Write((Int32)SizeX);
+                    bw.Write((Int32)SizeY);
+                    bw.Write((Int32)CompressionFactor);
+                    for (int yy = 0; yy < SizeY; yy++)
+                        for (int xx = 0; xx < SizeX; xx++)
+                        {
+                            bw.Write((Int16)m_heightmap[xx, yy]);
+                        }
+                }
+                ret = str.ToArray();
+            }
+            return ret;
+        }
+
+        // Initialize heightmap from blob consisting of:
+        //    int32, int32, int32, int32, int16[]
+        //    where the first int32 is format code, next two int32s are the X and y of heightmap data and
+        //    the forth int is the compression factor for the following int16s
+        // This is just sets heightmap info. The actual size of the region was set on this instance's
+        //    creation and any heights not initialized by theis blob are set to the default height.
+        public void FromCompressedTerrainSerialization(byte[] pBlob)
+        {
+            Int32 hmFormatCode, hmSizeX, hmSizeY, hmCompressionFactor;
+
+            using (MemoryStream mstr = new MemoryStream(pBlob))
+            {
+                using (BinaryReader br = new BinaryReader(mstr))
+                {
+                    hmFormatCode = br.ReadInt32();
+                    hmSizeX = br.ReadInt32();
+                    hmSizeY = br.ReadInt32();
+                    hmCompressionFactor = br.ReadInt32();
+
+                    m_compressionFactor = hmCompressionFactor;
+
+                    // In case database info doesn't match real terrain size, initialize the whole terrain.
+                    ClearLand();
+
+                    for (int yy = 0; yy < hmSizeY; yy++)
+                    {
+                        for (int xx = 0; xx < hmSizeX; xx++)
+                        {
+                            Int16 val = br.ReadInt16();
+                            if (xx < SizeX && yy < SizeY)
+                                m_heightmap[xx, yy] = val;
+                        }
+                    }
+                }
+                ClearTaint();
+
+                m_log.InfoFormat("{0} Read compressed 2d heightmap. Heightmap size=<{1},{2}>. Region size=<{3},{4}>. CompFact={5}",
+                                LogHeader, hmSizeX, hmSizeY, SizeX, SizeY, hmCompressionFactor);
+            }
+        }
+    }
+}
diff --git a/OpenSim/Region/CoreModules/World/Terrain/FileLoaders/GenericSystemDrawing.cs b/OpenSim/Region/CoreModules/World/Terrain/FileLoaders/GenericSystemDrawing.cs
index d78ade5..d5c77ec 100644
--- a/OpenSim/Region/CoreModules/World/Terrain/FileLoaders/GenericSystemDrawing.cs
+++ b/OpenSim/Region/CoreModules/World/Terrain/FileLoaders/GenericSystemDrawing.cs
@@ -67,7 +67,7 @@ namespace OpenSim.Region.CoreModules.World.Terrain.FileLoaders
         {
             using (Bitmap bitmap = new Bitmap(filename))
             {
-                ITerrainChannel retval = new TerrainChannel(true);
+                ITerrainChannel retval = new TerrainChannel(w, h);
 
                 for (int x = 0; x < retval.Width; x++)
                 {
diff --git a/OpenSim/Region/CoreModules/World/Terrain/TerrainModule.cs b/OpenSim/Region/CoreModules/World/Terrain/TerrainModule.cs
index 4d738a5..9a88804 100644
--- a/OpenSim/Region/CoreModules/World/Terrain/TerrainModule.cs
+++ b/OpenSim/Region/CoreModules/World/Terrain/TerrainModule.cs
@@ -71,6 +71,10 @@ namespace OpenSim.Region.CoreModules.World.Terrain
 
         private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
         
+#pragma warning disable 414
+        private static readonly string LogHeader = "[TERRAIN MODULE]";
+#pragma warning restore 414
+
         private readonly Commander m_commander = new Commander("terrain");
 
         private readonly Dictionary<StandardTerrainEffects, ITerrainFloodEffect> m_floodeffects =
@@ -81,8 +85,8 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         private readonly Dictionary<StandardTerrainEffects, ITerrainPaintableEffect> m_painteffects =
             new Dictionary<StandardTerrainEffects, ITerrainPaintableEffect>();
 
-        private ITerrainChannel m_channel;
         private Dictionary<string, ITerrainEffect> m_plugineffects;
+        private ITerrainChannel m_channel;
         private ITerrainChannel m_revert;
         private Scene m_scene;
         private volatile bool m_tainted;
@@ -90,6 +94,85 @@ namespace OpenSim.Region.CoreModules.World.Terrain
 
         private String m_InitialTerrain = "pinhead-island";
 
+        // If true, send terrain patch updates to clients based on their view distance
+        private bool m_sendTerrainUpdatesByViewDistance = true;
+
+        // Class to keep the per client collection of terrain patches that must be sent.
+        // A patch is set to 'true' meaning it should be sent to the client. Once the
+        //    patch packet is queued to the client, the bit for that patch is set to 'false'.
+        private class PatchUpdates
+        {
+            private bool[,] updated;    // for each patch, whether it needs to be sent to this client
+            private int updateCount;    // number of patches that need to be sent
+            public ScenePresence Presence;   // a reference to the client to send to
+            public PatchUpdates(TerrainData terrData, ScenePresence pPresence)
+            {
+                updated = new bool[terrData.SizeX / Constants.TerrainPatchSize, terrData.SizeY / Constants.TerrainPatchSize];
+                updateCount = 0;
+                Presence = pPresence;
+                // Initially, send all patches to the client
+                SetAll(true);
+            }
+            // Returns 'true' if there are any patches marked for sending
+            public bool HasUpdates()
+            {
+                return (updateCount > 0);
+            }
+            public void SetByXY(int x, int y, bool state)
+            {
+                this.SetByPatch(x / Constants.TerrainPatchSize, y / Constants.TerrainPatchSize, state);
+            }
+            public bool GetByPatch(int patchX, int patchY)
+            {
+                return updated[patchX, patchY];
+            }
+            public void SetByPatch(int patchX, int patchY, bool state)
+            {
+                bool prevState = updated[patchX, patchY];
+                if (!prevState && state)
+                    updateCount++;
+                if (prevState && !state)
+                    updateCount--;
+                updated[patchX, patchY] = state;
+            }
+            public void SetAll(bool state)
+            {
+                updateCount = 0;
+                for (int xx = 0; xx < updated.GetLength(0); xx++)
+                    for (int yy = 0; yy < updated.GetLength(1); yy++)
+                        updated[xx, yy] = state;
+                if (state)
+                    updateCount = updated.GetLength(0) * updated.GetLength(1);
+            }
+            // Logically OR's the terrain data's patch taint map into this client's update map.
+            public void SetAll(TerrainData terrData)
+            {
+                if (updated.GetLength(0) != (terrData.SizeX / Constants.TerrainPatchSize)
+                    || updated.GetLength(1) != (terrData.SizeY / Constants.TerrainPatchSize))
+                {
+                    throw new Exception(
+                        String.Format("{0} PatchUpdates.SetAll: patch array not same size as terrain. arr=<{1},{2}>, terr=<{3},{4}>",
+                                LogHeader, updated.GetLength(0), updated.GetLength(1),
+                                terrData.SizeX / Constants.TerrainPatchSize, terrData.SizeY / Constants.TerrainPatchSize)
+                    );
+                }
+                for (int xx = 0; xx < terrData.SizeX; xx += Constants.TerrainPatchSize)
+                {
+                    for (int yy = 0; yy < terrData.SizeY; yy += Constants.TerrainPatchSize)
+                    {
+                        // Only set tainted. The patch bit may be set if the patch was to be sent later.
+                        if (terrData.IsTaintedAt(xx, yy, false))
+                        {
+                            this.SetByXY(xx, yy, true);
+                        }
+                    }
+                }
+            }
+        }
+
+        // The flags of which terrain patches to send for each of the ScenePresence's
+        private Dictionary<UUID, PatchUpdates> m_perClientPatchUpdates = new Dictionary<UUID, PatchUpdates>();
+
         /// <summary>
         /// Human readable list of terrain file extensions that are supported.
         /// </summary>
@@ -118,7 +201,10 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         {
             IConfig terrainConfig = config.Configs["Terrain"];
             if (terrainConfig != null)
+            {
                 m_InitialTerrain = terrainConfig.GetString("InitialTerrain", m_InitialTerrain);
+                m_sendTerrainUpdatesByViewDistance = terrainConfig.GetBoolean("SendTerrainUpdatesByViewDistance", m_sendTerrainUpdatesByViewDistance);
+            }
         }
 
         public void AddRegion(Scene scene)
@@ -130,22 +216,24 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             {
                 if (m_scene.Heightmap == null)
                 {
-                    m_channel = new TerrainChannel(m_InitialTerrain);
+                    m_channel = new TerrainChannel(m_InitialTerrain, (int)m_scene.RegionInfo.RegionSizeX,
+                                                                     (int)m_scene.RegionInfo.RegionSizeY,
+                                                                     (int)m_scene.RegionInfo.RegionSizeZ);
                     m_scene.Heightmap = m_channel;
-                    m_revert = new TerrainChannel();
                     UpdateRevertMap();
                 }
                 else
                 {
                     m_channel = m_scene.Heightmap;
-                    m_revert = new TerrainChannel();
                     UpdateRevertMap();
                 }
 
                 m_scene.RegisterModuleInterface<ITerrainModule>(this);
                 m_scene.EventManager.OnNewClient += EventManager_OnNewClient;
+                m_scene.EventManager.OnClientClosed += EventManager_OnClientClosed;
                 m_scene.EventManager.OnPluginConsole += EventManager_OnPluginConsole;
                 m_scene.EventManager.OnTerrainTick += EventManager_OnTerrainTick;
+                m_scene.EventManager.OnFrame += EventManager_OnFrame;
             }
 
             InstallDefaultEffects();
@@ -184,8 +272,10 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                 // remove the commands
                 m_scene.UnregisterModuleCommander(m_commander.Name);
                 // remove the event-handlers
+                m_scene.EventManager.OnFrame -= EventManager_OnFrame;
                 m_scene.EventManager.OnTerrainTick -= EventManager_OnTerrainTick;
                 m_scene.EventManager.OnPluginConsole -= EventManager_OnPluginConsole;
+                m_scene.EventManager.OnClientClosed -= EventManager_OnClientClosed;
                 m_scene.EventManager.OnNewClient -= EventManager_OnNewClient;
                 // remove the interface
                 m_scene.UnregisterModuleInterface<ITerrainModule>(this);
@@ -230,11 +320,11 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                         try
                         {
                             ITerrainChannel channel = loader.Value.LoadFile(filename);
-                            if (channel.Width != Constants.RegionSize || channel.Height != Constants.RegionSize)
+                            if (channel.Width != m_scene.RegionInfo.RegionSizeX || channel.Height != m_scene.RegionInfo.RegionSizeY)
                             {
                                 // TerrainChannel expects a RegionSize x RegionSize map, currently
                                 throw new ArgumentException(String.Format("wrong size, use a file with size {0} x {1}",
-                                                                          Constants.RegionSize, Constants.RegionSize));
+                                                                          m_scene.RegionInfo.RegionSizeX, m_scene.RegionInfo.RegionSizeY));
                             }
                             m_log.DebugFormat("[TERRAIN]: Loaded terrain, wd/ht: {0}/{1}", channel.Width, channel.Height);
                             m_scene.Heightmap = channel;
@@ -261,7 +351,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                                 String.Format("Unable to load heightmap: {0}", e.Message));
                         }
                     }
-                    CheckForTerrainUpdates();
                     m_log.Info("[TERRAIN]: File (" + filename + ") loaded successfully");
                     return;
                 }
@@ -309,12 +398,18 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             LoadFromStream(filename, URIFetch(pathToTerrainHeightmap));
         }
 
+        public void LoadFromStream(string filename, Stream stream)
+        {
+            LoadFromStream(filename, Vector3.Zero, 0f, Vector2.Zero, stream);
+        }
+
         /// <summary>
         /// Loads a terrain file from a stream and installs it in the scene.
         /// </summary>
         /// <param name="filename">Filename to terrain file. Type is determined by extension.</param>
         /// <param name="stream"></param>
-        public void LoadFromStream(string filename, Stream stream)
+        public void LoadFromStream(string filename, Vector3 displacement,
+                                float radianRotation, Vector2 rotationDisplacement, Stream stream)
         {
             foreach (KeyValuePair<string, ITerrainLoader> loader in m_loaders)
             {
@@ -325,8 +420,7 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                         try
                         {
                             ITerrainChannel channel = loader.Value.LoadStream(stream);
-                            m_scene.Heightmap = channel;
-                            m_channel = channel;
+                            m_channel.Merge(channel, displacement, radianRotation, rotationDisplacement);
                             UpdateRevertMap();
                         }
                         catch (NotImplementedException)
@@ -337,7 +431,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                         }
                     }
 
-                    CheckForTerrainUpdates();
                     m_log.Info("[TERRAIN]: File (" + filename + ") loaded successfully");
                     return;
                 }
@@ -406,9 +499,46 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             }
         }
 
+        // Someone diddled terrain outside the normal code paths. Set the taintedness for all clients.
+        // ITerrainModule.TaintTerrain()
         public void TaintTerrain ()
         {
-            CheckForTerrainUpdates();
+            lock (m_perClientPatchUpdates)
+            {
+                // Set the flags for all clients so the tainted patches will be sent out
+                foreach (PatchUpdates pups in m_perClientPatchUpdates.Values)
+                {
+                    pups.SetAll(m_scene.Heightmap.GetTerrainData());
+                }
+            }
+        }
+
+        // ITerrainModule.PushTerrain()
+        public void PushTerrain(IClientAPI pClient)
+        {
+            if (m_sendTerrainUpdatesByViewDistance)
+            {
+                ScenePresence presence = m_scene.GetScenePresence(pClient.AgentId);
+                if (presence != null)
+                {
+                    lock (m_perClientPatchUpdates)
+                    {
+                        PatchUpdates pups;
+                        if (!m_perClientPatchUpdates.TryGetValue(pClient.AgentId, out pups))
+                        {
+                            // There is a ScenePresence without a send patch map. Create one.
+                            pups = new PatchUpdates(m_scene.Heightmap.GetTerrainData(), presence);
+                            m_perClientPatchUpdates.Add(presence.UUID, pups);
+                        }
+                        pups.SetAll(true);
+                    }
+                }
+            }
+            else
+            {
+                // The traditional way is to call into the protocol stack to send them all.
+                pClient.SendLayerData(new float[10]);
+            }
         }
 
         #region Plugin Loading Methods
@@ -532,6 +662,7 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         /// </summary>
         public void UpdateRevertMap()
         {
+            /*
             int x;
             for (x = 0; x < m_channel.Width; x++)
             {
@@ -541,6 +672,8 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                     m_revert[x, y] = m_channel[x, y];
                 }
             }
+             */
+            m_revert = m_channel.MakeCopy();
         }
 
         /// <summary>
@@ -567,8 +700,8 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                         {
                             ITerrainChannel channel = loader.Value.LoadFile(filename, offsetX, offsetY,
                                                                             fileWidth, fileHeight,
-                                                                            (int) Constants.RegionSize,
-                                                                            (int) Constants.RegionSize);
+                                                                            (int) m_scene.RegionInfo.RegionSizeX,
+                                                                            (int) m_scene.RegionInfo.RegionSizeY);
                             m_scene.Heightmap = channel;
                             m_channel = channel;
                             UpdateRevertMap();
@@ -615,8 +748,8 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                     {
                         loader.Value.SaveFile(m_channel, filename, offsetX, offsetY,
                                               fileWidth, fileHeight,
-                                              (int)Constants.RegionSize,
-                                              (int)Constants.RegionSize);
+                                              (int)m_scene.RegionInfo.RegionSizeX,
+                                              (int)m_scene.RegionInfo.RegionSizeY);
 
                         MainConsole.Instance.OutputFormat(
                             "Saved terrain from ({0},{1}) to ({2},{3}) from {4} to {5}",
@@ -634,7 +767,44 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         }
 
         /// <summary>
+        /// Called before processing of every simulation frame.
+        /// This is used to check to see of any of the terrain is tainted and, if so, schedule
+        /// updates for all the presences.
+        /// This also checks to see if there are updates that need to be sent for each presence.
+        /// This is where the logic is to send terrain updates to clients.
+        /// </summary>
+        private void EventManager_OnFrame()
+        {
+            TerrainData terrData = m_channel.GetTerrainData();
+
+            bool shouldTaint = false;
+            for (int x = 0; x < terrData.SizeX; x += Constants.TerrainPatchSize)
+            {
+                for (int y = 0; y < terrData.SizeY; y += Constants.TerrainPatchSize)
+                {
+                    if (terrData.IsTaintedAt(x, y))
+                    {
+                        // Found a patch that was modified. Push this flag into the clients.
+                        SendToClients(terrData, x, y);
+                        shouldTaint = true;
+                    }
+                }
+            }
+
+            // This event also causes changes to be sent to the clients
+            CheckSendingPatchesToClients();
+
+            // If things changes, generate some events
+            if (shouldTaint)
+            {
+                m_scene.EventManager.TriggerTerrainTainted();
+                m_tainted = true;
+            }
+        }
+
+        /// <summary>
         /// Performs updates to the region periodically, synchronising physics and other heightmap aware sections
+        /// Called infrequently (like every 5 seconds or so). Best used for storing terrain.
         /// </summary>
         private void EventManager_OnTerrainTick()
         {
@@ -644,8 +814,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                 m_scene.PhysicsScene.SetTerrain(m_channel.GetFloatsSerialised());
                 m_scene.SaveTerrain();
 
-                m_scene.EventManager.TriggerTerrainUpdate();
-
                 // Clients who look at the map will never see changes after they looked at the map, so i've commented this out.
                 //m_scene.CreateTerrainTexture(true);
             }
@@ -687,54 +855,48 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         }
         
         /// <summary>
-        /// Checks to see if the terrain has been modified since last check
-        /// but won't attempt to limit those changes to the limits specified in the estate settings
-        /// currently invoked by the command line operations in the region server only
+        /// Installs terrain brush hook to IClientAPI
         /// </summary>
-        private void CheckForTerrainUpdates()
+        /// <param name="client"></param>
+        private void EventManager_OnClientClosed(UUID client, Scene scene)
         {
-            CheckForTerrainUpdates(false);
-        }
+            ScenePresence presence = scene.GetScenePresence(client);
+            if (presence != null)
+            {
+                presence.ControllingClient.OnModifyTerrain -= client_OnModifyTerrain;
+                presence.ControllingClient.OnBakeTerrain -= client_OnBakeTerrain;
+                presence.ControllingClient.OnLandUndo -= client_OnLandUndo;
+                presence.ControllingClient.OnUnackedTerrain -= client_OnUnackedTerrain;
+            }
 
+            lock (m_perClientPatchUpdates)
+                m_perClientPatchUpdates.Remove(client);
+        }
+        
         /// <summary>
-        /// Checks to see if the terrain has been modified since last check.
-        /// If it has been modified, every all the terrain patches are sent to the client.
-        /// If the call is asked to respect the estate settings for terrain_raise_limit and
-        /// terrain_lower_limit, it will clamp terrain updates between these values
-        /// currently invoked by client_OnModifyTerrain only and not the Commander interfaces
-        /// <param name="respectEstateSettings">should height map deltas be limited to the estate settings limits</param>
+        /// Scan over changes in the terrain and limit height changes. This enforces the
+        ///     non-estate owner limits on rate of terrain editting.
+        /// Returns 'true' if any heights were limited.
         /// </summary>
-        private void CheckForTerrainUpdates(bool respectEstateSettings)
+        private bool EnforceEstateLimits()
         {
-            bool shouldTaint = false;
-            float[] serialised = m_channel.GetFloatsSerialised();
-            int x;
-            for (x = 0; x < m_channel.Width; x += Constants.TerrainPatchSize)
+            TerrainData terrData = m_channel.GetTerrainData();
+
+            bool wasLimited = false;
+            for (int x = 0; x < terrData.SizeX; x += Constants.TerrainPatchSize)
             {
-                int y;
-                for (y = 0; y < m_channel.Height; y += Constants.TerrainPatchSize)
+                for (int y = 0; y < terrData.SizeY; y += Constants.TerrainPatchSize)
                 {
-                    if (m_channel.Tainted(x, y))
-                    {
-                        // if we should respect the estate settings then
-                        // fixup and height deltas that don't respect them
-                        if (respectEstateSettings && LimitChannelChanges(x, y))
-                        {
-                            // this has been vetoed, so update
-                            // what we are going to send to the client
-                            serialised = m_channel.GetFloatsSerialised();
-                        }
-
-                        SendToClients(serialised, x, y);
-                        shouldTaint = true;
+                    if (terrData.IsTaintedAt(x, y, false /* clearOnTest */))
+                   {
+                        // If we should respect the estate settings then
+                        //     fixup and height deltas that don't respect them.
+                        // Note that LimitChannelChanges() modifies the TerrainChannel with the limited height values.
+                        wasLimited |= LimitChannelChanges(terrData, x, y);
                     }
                 }
             }
-            if (shouldTaint)
-            {
-                m_scene.EventManager.TriggerTerrainTainted();
-                m_tainted = true;
-            }
+            return wasLimited;
         }
 
         /// <summary>
@@ -742,11 +904,11 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         /// are all within the current estate limits
         /// <returns>true if changes were limited, false otherwise</returns>
         /// </summary>
-        private bool LimitChannelChanges(int xStart, int yStart)
+        private bool LimitChannelChanges(TerrainData terrData, int xStart, int yStart)
         {
             bool changesLimited = false;
-            double minDelta = m_scene.RegionInfo.RegionSettings.TerrainLowerLimit;
-            double maxDelta = m_scene.RegionInfo.RegionSettings.TerrainRaiseLimit;
+            float minDelta = (float)m_scene.RegionInfo.RegionSettings.TerrainLowerLimit;
+            float maxDelta = (float)m_scene.RegionInfo.RegionSettings.TerrainRaiseLimit;
 
             // loop through the height map for this patch and compare it against
             // the revert map
@@ -754,19 +916,18 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             {
                 for (int y = yStart; y < yStart + Constants.TerrainPatchSize; y++)
                 {
-
-                    double requestedHeight = m_channel[x, y];
-                    double bakedHeight = m_revert[x, y];
-                    double requestedDelta = requestedHeight - bakedHeight;
+                    float requestedHeight = terrData[x, y];
+                    float bakedHeight = (float)m_revert[x, y];
+                    float requestedDelta = requestedHeight - bakedHeight;
 
                     if (requestedDelta > maxDelta)
                     {
-                        m_channel[x, y] = bakedHeight + maxDelta;
+                        terrData[x, y] = bakedHeight + maxDelta;
                         changesLimited = true;
                     }
                     else if (requestedDelta < minDelta)
                     {
-                        m_channel[x, y] = bakedHeight + minDelta; //as lower is a -ve delta
+                        terrData[x, y] = bakedHeight + minDelta; //as lower is a -ve delta
                         changesLimited = true;
                     }
                 }
@@ -794,14 +955,154 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         /// <param name="serialised">A copy of the terrain as a 1D float array of size w*h</param>
         /// <param name="x">The patch corner to send</param>
         /// <param name="y">The patch corner to send</param>
-        private void SendToClients(float[] serialised, int x, int y)
+        private void SendToClients(TerrainData terrData, int x, int y)
+        {
+            if (m_sendTerrainUpdatesByViewDistance)
+            {
+                // Add that this patch needs to be sent to the accounting for each client.
+                lock (m_perClientPatchUpdates)
+                {
+                    m_scene.ForEachScenePresence(presence =>
+                        {
+                            PatchUpdates thisClientUpdates;
+                            if (!m_perClientPatchUpdates.TryGetValue(presence.UUID, out thisClientUpdates))
+                            {
+                                // There is a ScenePresence without a send patch map. Create one.
+                                thisClientUpdates = new PatchUpdates(terrData, presence);
+                                m_perClientPatchUpdates.Add(presence.UUID, thisClientUpdates);
+                            }
+                            thisClientUpdates.SetByXY(x, y, true);
+                        }
+                    );
+                }
+            }
+            else
+            {
+                // Legacy update sending where the update is sent out as soon as noticed
+                // We know the actual terrain data passed is ignored. This kludge saves changing IClientAPI.
+                //float[] heightMap = terrData.GetFloatsSerialized();
+                float[] heightMap = new float[10];
+                m_scene.ForEachClient(
+                    delegate(IClientAPI controller)
+                    {
+                        controller.SendLayerData(x / Constants.TerrainPatchSize,
+                                                 y / Constants.TerrainPatchSize,
+                                                 heightMap);
+                    }
+                );
+            }
+        }
+
+        private class PatchesToSend : IComparable<PatchesToSend>
         {
-            m_scene.ForEachClient(
-                delegate(IClientAPI controller)
-                    { controller.SendLayerData(
-                        x / Constants.TerrainPatchSize, y / Constants.TerrainPatchSize, serialised);
+            public int PatchX;
+            public int PatchY;
+            public float Dist;
+            public PatchesToSend(int pX, int pY, float pDist)
+            {
+                PatchX = pX;
+                PatchY = pY;
+                Dist = pDist;
+            }
+            public int CompareTo(PatchesToSend other)
+            {
+                return Dist.CompareTo(other.Dist);
+            }
+        }
+
+        // Called each frame time to see if there are any patches to send to any of the
+        //    ScenePresences.
+        // Loop through all the per-client info and send any patches necessary.
+        private void CheckSendingPatchesToClients()
+        {
+            lock (m_perClientPatchUpdates)
+            {
+                foreach (PatchUpdates pups in m_perClientPatchUpdates.Values)
+                {
+                    if (pups.HasUpdates())
+                    {
+                        // There is something that could be sent to this client.
+                        List<PatchesToSend> toSend = GetModifiedPatchesInViewDistance(pups);
+                        if (toSend.Count > 0)
+                        {
+                            // m_log.DebugFormat("{0} CheckSendingPatchesToClient: sending {1} patches to {2} in region {3}",
+                            //                     LogHeader, toSend.Count, pups.Presence.Name, m_scene.RegionInfo.RegionName);
+                            // Sort the patches to send by the distance from the presence
+                            toSend.Sort();
+                            /*
+                            foreach (PatchesToSend pts in toSend)
+                            {
+                                pups.Presence.ControllingClient.SendLayerData(pts.PatchX, pts.PatchY, null);
+                                // presence.ControllingClient.SendLayerData(xs.ToArray(), ys.ToArray(), null, TerrainPatch.LayerType.Land);
+                            }
+                            */
+
+                            int[] xPieces = new int[toSend.Count];
+                            int[] yPieces = new int[toSend.Count];
+                            float[] patchPieces = new float[toSend.Count * 2];
+                            int pieceIndex = 0;
+                            foreach (PatchesToSend pts in toSend)
+                            {
+                                patchPieces[pieceIndex++] = pts.PatchX;
+                                patchPieces[pieceIndex++] = pts.PatchY;
+                            }
+                            pups.Presence.ControllingClient.SendLayerData(-toSend.Count, 0, patchPieces);
+                        }
+                    }
+                }
+            }
+        }
+
+        private List<PatchesToSend> GetModifiedPatchesInViewDistance(PatchUpdates pups)
+        {
+            List<PatchesToSend> ret = new List<PatchesToSend>();
+
+            ScenePresence presence = pups.Presence;
+            if (presence == null)
+                return ret;
+
+            // Compute the area of patches within our draw distance
+            int startX = (((int) (presence.AbsolutePosition.X - presence.DrawDistance))/Constants.TerrainPatchSize) - 2;
+            startX = Math.Max(startX, 0);
+            startX = Math.Min(startX, (int)m_scene.RegionInfo.RegionSizeX/Constants.TerrainPatchSize);
+            int startY = (((int) (presence.AbsolutePosition.Y - presence.DrawDistance))/Constants.TerrainPatchSize) - 2;
+            startY = Math.Max(startY, 0);
+            startY = Math.Min(startY, (int)m_scene.RegionInfo.RegionSizeY/Constants.TerrainPatchSize);
+            int endX = (((int) (presence.AbsolutePosition.X + presence.DrawDistance))/Constants.TerrainPatchSize) + 2;
+            endX = Math.Max(endX, 0);
+            endX = Math.Min(endX, (int)m_scene.RegionInfo.RegionSizeX/Constants.TerrainPatchSize);
+            int endY = (((int) (presence.AbsolutePosition.Y + presence.DrawDistance))/Constants.TerrainPatchSize) + 2;
+            endY = Math.Max(endY, 0);
+            endY = Math.Min(endY, (int)m_scene.RegionInfo.RegionSizeY/Constants.TerrainPatchSize);
+            // m_log.DebugFormat("{0} GetModifiedPatchesInViewDistance. rName={1}, ddist={2}, apos={3}, start=<{4},{5}>, end=<{6},{7}>",
+            //                                     LogHeader, m_scene.RegionInfo.RegionName,
+            //                                     presence.DrawDistance, presence.AbsolutePosition,
+            //                                     startX, startY, endX, endY);
+            for (int x = startX; x < endX; x++)
+            {
+                for (int y = startY; y < endY; y++)
+                {
+                    //Need to make sure we don't send the same ones over and over
+                    Vector3 presencePos = presence.AbsolutePosition;
+                    Vector3 patchPos = new Vector3(x * Constants.TerrainPatchSize, y * Constants.TerrainPatchSize, presencePos.Z);
+                    if (pups.GetByPatch(x, y))
+                    {
+                        //Check which has less distance, camera or avatar position, both have to be done.
+                        //Its not a radius, its a diameter and we add 50 so that it doesn't look like it cuts off
+                        if (Util.DistanceLessThan(presencePos, patchPos, presence.DrawDistance + 50)
+                            || Util.DistanceLessThan(presence.CameraPosition, patchPos, presence.DrawDistance + 50))
+                        {
+                            //They can see it, send it to them
+                            pups.SetByPatch(x, y, false);
+                            float dist = Vector3.DistanceSquared(presencePos, patchPos);
+                            ret.Add(new PatchesToSend(x, y, dist));
+                            //Wait and send them all at once
+                            // pups.client.SendLayerData(x, y, null);
+                        }
                     }
-            );
+                }
+            }
+            return ret;
         }
 
         private void client_OnModifyTerrain(UUID user, float height, float seconds, byte size, byte action,
@@ -846,7 +1147,9 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                         m_painteffects[(StandardTerrainEffects) action].PaintEffect(
                             m_channel, allowMask, west, south, height, size, seconds);
 
-                        CheckForTerrainUpdates(!god); //revert changes outside estate limits
+                        //revert changes outside estate limits
+                        if (!god)
+                            EnforceEstateLimits();
                     }
                 }
                 else
@@ -884,10 +1187,11 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                     if (allowed)
                     {
                         StoreUndoState();
-                        m_floodeffects[(StandardTerrainEffects) action].FloodEffect(
-                            m_channel, fillArea, size);
+                        m_floodeffects[(StandardTerrainEffects) action].FloodEffect(m_channel, fillArea, size);
 
-                        CheckForTerrainUpdates(!god); //revert changes outside estate limits
+                        //revert changes outside estate limits
+                        if (!god)
+                            EnforceEstateLimits();
                     }
                 }
                 else
@@ -911,7 +1215,9 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         protected void client_OnUnackedTerrain(IClientAPI client, int patchX, int patchY)
         {
             //m_log.Debug("Terrain packet unacked, resending patch: " + patchX + " , " + patchY);
-             client.SendLayerData(patchX, patchY, m_scene.Heightmap.GetFloatsSerialised());
+            // SendLayerData does not use the heightmap parameter. This kludge is so as to not change IClientAPI.
+            float[] heightMap = new float[10];
+            client.SendLayerData(patchX, patchY, heightMap);
         }
 
         private void StoreUndoState()
@@ -938,7 +1244,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
         private void InterfaceLoadFile(Object[] args)
         {
             LoadFromFile((string) args[0]);
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceLoadTileFile(Object[] args)
@@ -948,7 +1253,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                          (int) args[2],
                          (int) args[3],
                          (int) args[4]);
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceSaveFile(Object[] args)
@@ -977,7 +1281,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                 for (y = 0; y < m_channel.Height; y++)
                     m_channel[x, y] = m_revert[x, y];
 
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceFlipTerrain(Object[] args)
@@ -986,28 +1289,28 @@ namespace OpenSim.Region.CoreModules.World.Terrain
 
             if (direction.ToLower().StartsWith("y"))
             {
-                for (int x = 0; x < Constants.RegionSize; x++)
+                for (int x = 0; x < m_channel.Width; x++)
                 {
-                    for (int y = 0; y < Constants.RegionSize / 2; y++)
+                    for (int y = 0; y < m_channel.Height / 2; y++)
                     {
                         double height = m_channel[x, y];
-                        double flippedHeight = m_channel[x, (int)Constants.RegionSize - 1 - y];
+                        double flippedHeight = m_channel[x, (int)m_channel.Height - 1 - y];
                         m_channel[x, y] = flippedHeight;
-                        m_channel[x, (int)Constants.RegionSize - 1 - y] = height;
+                        m_channel[x, (int)m_channel.Height - 1 - y] = height;
 
                     }
                 }
             }
             else if (direction.ToLower().StartsWith("x"))
             {
-                for (int y = 0; y < Constants.RegionSize; y++)
+                for (int y = 0; y < m_channel.Height; y++)
                 {
-                    for (int x = 0; x < Constants.RegionSize / 2; x++)
+                    for (int x = 0; x < m_channel.Width / 2; x++)
                     {
                         double height = m_channel[x, y];
-                        double flippedHeight = m_channel[(int)Constants.RegionSize - 1 - x, y];
+                        double flippedHeight = m_channel[(int)m_channel.Width - 1 - x, y];
                         m_channel[x, y] = flippedHeight;
-                        m_channel[(int)Constants.RegionSize - 1 - x, y] = height;
+                        m_channel[(int)m_channel.Width - 1 - x, y] = height;
 
                     }
                 }
@@ -1016,9 +1319,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             {
                 m_log.Error("Unrecognised direction - need x or y");
             }
-
-
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceRescaleTerrain(Object[] args)
@@ -1076,7 +1376,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                     }
                 }
 
-                CheckForTerrainUpdates();
             }
 
         }
@@ -1087,7 +1386,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             for (x = 0; x < m_channel.Width; x++)
                 for (y = 0; y < m_channel.Height; y++)
                     m_channel[x, y] += (double) args[0];
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceMultiplyTerrain(Object[] args)
@@ -1096,7 +1394,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             for (x = 0; x < m_channel.Width; x++)
                 for (y = 0; y < m_channel.Height; y++)
                     m_channel[x, y] *= (double) args[0];
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceLowerTerrain(Object[] args)
@@ -1105,17 +1402,15 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             for (x = 0; x < m_channel.Width; x++)
                 for (y = 0; y < m_channel.Height; y++)
                     m_channel[x, y] -= (double) args[0];
-            CheckForTerrainUpdates();
         }
 
-        private void InterfaceFillTerrain(Object[] args)
+        public void InterfaceFillTerrain(Object[] args)
         {
             int x, y;
 
             for (x = 0; x < m_channel.Width; x++)
                 for (y = 0; y < m_channel.Height; y++)
                     m_channel[x, y] = (double) args[0];
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceMinTerrain(Object[] args)
@@ -1128,7 +1423,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                     m_channel[x, y] = Math.Max((double)args[0], m_channel[x, y]);
                 }
             }
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceMaxTerrain(Object[] args)
@@ -1141,7 +1435,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
                     m_channel[x, y] = Math.Min((double)args[0], m_channel[x, y]);
                 }
             }
-            CheckForTerrainUpdates();
         }
 
         private void InterfaceShowDebugStats(Object[] args)
@@ -1204,7 +1497,6 @@ namespace OpenSim.Region.CoreModules.World.Terrain
             if (m_plugineffects.ContainsKey(firstArg))
             {
                 m_plugineffects[firstArg].RunEffect(m_channel);
-                CheckForTerrainUpdates();
             }
             else
             {
diff --git a/OpenSim/Region/Framework/Interfaces/ISimulationDataService.cs b/OpenSim/Region/Framework/Interfaces/ISimulationDataService.cs
index 3e97a7a..13358cb 100644
--- a/OpenSim/Region/Framework/Interfaces/ISimulationDataService.cs
+++ b/OpenSim/Region/Framework/Interfaces/ISimulationDataService.cs
@@ -68,13 +68,22 @@ namespace OpenSim.Region.Framework.Interfaces
         /// </summary>
         /// <param name="ter">HeightField data</param>
         /// <param name="regionID">region UUID</param>
+        void StoreTerrain(TerrainData terrain, UUID regionID);
+
+        // Legacy version kept for downward compabibility
         void StoreTerrain(double[,] terrain, UUID regionID);
 
         /// <summary>
         /// Load the latest terrain revision from region storage
         /// </summary>
         /// <param name="regionID">the region UUID</param>
+        /// <param name="sizeX">the X dimension of the region being filled</param>
+        /// <param name="sizeY">the Y dimension of the region being filled</param>
+        /// <param name="sizeZ">the Z dimension of the region being filled</param>
         /// <returns>Heightfield data</returns>
+        TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ);
+
+        // Legacy version kept for downward compabibility
         double[,] LoadTerrain(UUID regionID);
 
         void StoreLandObject(ILandObject Parcel);
diff --git a/OpenSim/Region/Framework/Interfaces/ISimulationDataStore.cs b/OpenSim/Region/Framework/Interfaces/ISimulationDataStore.cs
index 17bd48b..e09f775 100644
--- a/OpenSim/Region/Framework/Interfaces/ISimulationDataStore.cs
+++ b/OpenSim/Region/Framework/Interfaces/ISimulationDataStore.cs
@@ -79,13 +79,22 @@ namespace OpenSim.Region.Framework.Interfaces
         /// </summary>
         /// <param name="ter">HeightField data</param>
         /// <param name="regionID">region UUID</param>
+        void StoreTerrain(TerrainData terrain, UUID regionID);
+
+        // Legacy version kept for downward compabibility
         void StoreTerrain(double[,] terrain, UUID regionID);
         
         /// <summary>
         /// Load the latest terrain revision from region storage
         /// </summary>
         /// <param name="regionID">the region UUID</param>
+        /// <param name="pSizeX">the X dimension of the terrain being filled</param>
+        /// <param name="pSizeY">the Y dimension of the terrain being filled</param>
+        /// <param name="pSizeZ">the Z dimension of the terrain being filled</param>
         /// <returns>Heightfield data</returns>
+        TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ);
+
+        // Legacy version kept for downward compabibility
         double[,] LoadTerrain(UUID regionID);
 
         void StoreLandObject(ILandObject Parcel);
@@ -136,4 +145,5 @@ namespace OpenSim.Region.Framework.Interfaces
 
         void Shutdown();
     }
+
 }
diff --git a/OpenSim/Region/Framework/Interfaces/ITerrainChannel.cs b/OpenSim/Region/Framework/Interfaces/ITerrainChannel.cs
index e467701..f660b8d 100644
--- a/OpenSim/Region/Framework/Interfaces/ITerrainChannel.cs
+++ b/OpenSim/Region/Framework/Interfaces/ITerrainChannel.cs
@@ -25,13 +25,23 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+using OpenSim.Framework;
+using OpenMetaverse;
+
 namespace OpenSim.Region.Framework.Interfaces
 {
     public interface ITerrainChannel
     {
-        int Height { get; }
+        int Width { get;}       // X dimension
+        int Height { get;}      // Y dimension
+        int Altitude { get;}    // Z dimension
+
         double this[int x, int y] { get; set; }
-        int Width { get; }
+
+        float GetHeightAtXYZ(float x, float y, float z);
+
+        // Return the packaged terrain data for passing into lower levels of communication
+        TerrainData GetTerrainData();
 
         /// <summary>
         /// Squash the entire heightmap into a single dimensioned array
@@ -40,9 +50,14 @@ namespace OpenSim.Region.Framework.Interfaces
         float[] GetFloatsSerialised();
 
         double[,] GetDoubles();
+
+        // Check if a location has been updated. Clears the taint flag as a side effect.
         bool Tainted(int x, int y);
+
         ITerrainChannel MakeCopy();
         string SaveToXmlString();
         void LoadFromXmlString(string data);
+        // Merge some terrain into this channel
+        void Merge(ITerrainChannel newTerrain, Vector3 displacement, float radianRotation, Vector2 rotationDisplacement);
     }
 }
diff --git a/OpenSim/Region/Framework/Scenes/Scene.cs b/OpenSim/Region/Framework/Scenes/Scene.cs
index 03270d7..f5458c1 100644
--- a/OpenSim/Region/Framework/Scenes/Scene.cs
+++ b/OpenSim/Region/Framework/Scenes/Scene.cs
@@ -1935,7 +1935,7 @@ namespace OpenSim.Region.Framework.Scenes
         {
             try
             {
-                double[,] map = SimulationDataService.LoadTerrain(RegionInfo.RegionID);
+                TerrainData map = SimulationDataService.LoadTerrain(RegionInfo.RegionID, (int)RegionInfo.RegionSizeX, (int)RegionInfo.RegionSizeY, (int)RegionInfo.RegionSizeZ);
                 if (map == null)
                 {
                     // This should be in the Terrain module, but it isn't because
@@ -1946,7 +1946,7 @@ namespace OpenSim.Region.Framework.Scenes
                         m_InitialTerrain = terrainConfig.GetString("InitialTerrain", m_InitialTerrain);
 
                     m_log.InfoFormat("[TERRAIN]: No default terrain. Generating a new terrain {0}.", m_InitialTerrain);
-                    Heightmap = new TerrainChannel(m_InitialTerrain);
+                    Heightmap = new TerrainChannel(m_InitialTerrain, (int)RegionInfo.RegionSizeX, (int)RegionInfo.RegionSizeY, (int)RegionInfo.RegionSizeZ);
 
                     SimulationDataService.StoreTerrain(Heightmap.GetDoubles(), RegionInfo.RegionID);
                 }
diff --git a/OpenSim/Region/Framework/Scenes/TerrainChannel.cs b/OpenSim/Region/Framework/Scenes/TerrainChannel.cs
index b6e0a97..3d563a6 100644
--- a/OpenSim/Region/Framework/Scenes/TerrainChannel.cs
+++ b/OpenSim/Region/Framework/Scenes/TerrainChannel.cs
@@ -25,14 +25,21 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-using OpenSim.Framework;
-using OpenSim.Region.Framework.Interfaces;
 using System;
+using System.IO;
 using System.Text;
+using System.Reflection;
 using System.Xml;
-using System.IO;
 using System.Xml.Serialization;
 
+using OpenSim.Data;
+using OpenSim.Framework;
+using OpenSim.Region.Framework.Interfaces;
+
+using OpenMetaverse;
+
+using log4net;
+
 namespace OpenSim.Region.Framework.Scenes
 {
     /// <summary>
@@ -40,140 +47,136 @@ namespace OpenSim.Region.Framework.Scenes
     /// </summary>
     public class TerrainChannel : ITerrainChannel
     {
-        private readonly bool[,] taint;
-        private double[,] map;
+        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+        private static string LogHeader = "[TERRAIN CHANNEL]";
 
+        protected TerrainData m_terrainData;
+
+        public int Width { get { return m_terrainData.SizeX; } }  // X dimension
+        // Unfortunately, for historical reasons, in this module 'Width' is X and 'Height' is Y
+        public int Height { get { return m_terrainData.SizeY; } } // Y dimension
+        public int Altitude { get { return m_terrainData.SizeZ; } } // Y dimension
+
+        // Default, not-often-used builder
         public TerrainChannel()
         {
-            map = new double[Constants.RegionSize, Constants.RegionSize];
-            taint = new bool[Constants.RegionSize / 16, Constants.RegionSize / 16];
-
-            PinHeadIsland();
+            m_terrainData = new HeightmapTerrainData((int)Constants.RegionSize, (int)Constants.RegionSize, (int)Constants.RegionHeight);
+            FlatLand();
+            // PinHeadIsland();
         }
 
-        public TerrainChannel(String type)
+        // Create terrain of given size
+        public TerrainChannel(int pX, int pY)
         {
-            map = new double[Constants.RegionSize, Constants.RegionSize];
-            taint = new bool[Constants.RegionSize / 16, Constants.RegionSize / 16];
+            m_terrainData = new HeightmapTerrainData(pX, pY, (int)Constants.RegionHeight);
+        }
 
+        // Create terrain of specified size and initialize with specified terrain.
+        // TODO: join this with the terrain initializers.
+        public TerrainChannel(String type, int pX, int pY, int pZ)
+        {
+            m_terrainData = new HeightmapTerrainData(pX, pY, pZ);
             if (type.Equals("flat"))
                 FlatLand();
             else
                 PinHeadIsland();
         }
 
-        public TerrainChannel(double[,] import)
+        // Create channel passed a heightmap and expected dimensions of the region.
+        // The heightmap might not fit the passed size so accomodations must be made.
+        public TerrainChannel(double[,] pM, int pSizeX, int pSizeY, int pAltitude)
         {
-            map = import;
-            taint = new bool[import.GetLength(0),import.GetLength(1)];
-        }
+            int hmSizeX = pM.GetLength(0);
+            int hmSizeY = pM.GetLength(1);
 
-        public TerrainChannel(bool createMap)
-        {
-            if (createMap)
-            {
-                map = new double[Constants.RegionSize,Constants.RegionSize];
-                taint = new bool[Constants.RegionSize / 16,Constants.RegionSize / 16];
-            }
+            m_terrainData = new HeightmapTerrainData(pSizeX, pSizeY, pAltitude);
+
+            for (int xx = 0; xx < pSizeX; xx++)
+                for (int yy = 0; yy < pSizeY; yy++)
+                    if (xx > hmSizeX || yy > hmSizeY)
+                        m_terrainData[xx, yy] = TerrainData.DefaultTerrainHeight;
+                    else
+                        m_terrainData[xx, yy] = (float)pM[xx, yy];
         }
 
-        public TerrainChannel(int w, int h)
+        public TerrainChannel(TerrainData pTerrData)
         {
-            map = new double[w,h];
-            taint = new bool[w / 16,h / 16];
+            m_terrainData = pTerrData;
         }
 
         #region ITerrainChannel Members
 
-        public int Width
+        // ITerrainChannel.MakeCopy()
+        public ITerrainChannel MakeCopy()
         {
-            get { return map.GetLength(0); }
+            return this.Copy();
         }
 
-        public int Height
+        // ITerrainChannel.GetTerrainData()
+        public TerrainData GetTerrainData()
         {
-            get { return map.GetLength(1); }
+            return m_terrainData;
         }
 
-        public ITerrainChannel MakeCopy()
+        // ITerrainChannel.GetFloatsSerialized()
+        // This one dimensional version is ordered so height = map[y*sizeX+x];
+        // DEPRECATED: don't use this function as it does not retain the dimensions of the terrain
+        //     and the caller will probably do the wrong thing if the terrain is not the legacy 256x256.
+        public float[] GetFloatsSerialised()
         {
-            TerrainChannel copy = new TerrainChannel(false);
-            copy.map = (double[,]) map.Clone();
-
-            return copy;
+            return m_terrainData.GetFloatsSerialized();
         }
 
-        public float[] GetFloatsSerialised()
+        // ITerrainChannel.GetDoubles()
+        public double[,] GetDoubles()
         {
-            // Move the member variables into local variables, calling
-            // member variables 256*256 times gets expensive
-            int w = Width;
-            int h = Height;
-            float[] heights = new float[w * h];
+            double[,] heights = new double[Width, Height];
 
-            int i, j; // map coordinates
             int idx = 0; // index into serialized array
-            for (i = 0; i < h; i++)
+            for (int ii = 0; ii < Width; ii++)
             {
-                for (j = 0; j < w; j++)
+                for (int jj = 0; jj < Height; jj++)
                 {
-                    heights[idx++] = (float)map[j, i];
+                    heights[ii, jj] = (double)m_terrainData[ii, jj];
+                    idx++;
                 }
             }
 
             return heights;
         }
 
-        public double[,] GetDoubles()
-        {
-            return map;
-        }
-
+        // ITerrainChannel.this[x,y]
         public double this[int x, int y]
         {
-            get
-            {
-                if (x < 0) x = 0;
-                if (y < 0) y = 0;
-                if (x >= (int)Constants.RegionSize) x = (int)Constants.RegionSize - 1;
-                if (y >= (int)Constants.RegionSize) y = (int)Constants.RegionSize - 1;
-
-                return map[x, y];
+            get {
+                if (x < 0 || x >= Width || y < 0 || y >= Height)
+                    return 0;
+                return (double)m_terrainData[x, y];
             }
             set
             {
-                // Will "fix" terrain hole problems. Although not fantastically.
                 if (Double.IsNaN(value) || Double.IsInfinity(value))
                     return;
 
-                if (map[x, y] != value)
-                {
-                    taint[x / 16, y / 16] = true;
-                    map[x, y] = value;
-                }
+                m_terrainData[x, y] = (float)value;
             }
         }
 
-        public bool Tainted(int x, int y)
+        // ITerrainChannel.GetHieghtAtXYZ(x, y, z)
+        public float GetHeightAtXYZ(float x, float y, float z)
         {
-            if (taint[x / 16, y / 16])
-            {
-                taint[x / 16, y / 16] = false;
-                return true;
-            }
-            return false;
+            if (x < 0 || x >= Width || y < 0 || y >= Height)
+                return 0;
+            return m_terrainData[(int)x, (int)y];
         }
 
-        #endregion
-
-        public TerrainChannel Copy()
+        // ITerrainChannel.Tainted()
+        public bool Tainted(int x, int y)
         {
-            TerrainChannel copy = new TerrainChannel(false);
-            copy.map = (double[,]) map.Clone();
-
-            return copy;
+            return m_terrainData.IsTaintedAt(x, y);
         }
 
+        // ITerrainChannel.SaveToXmlString()
         public string SaveToXmlString()
         {
             XmlWriterSettings settings = new XmlWriterSettings();
@@ -189,13 +192,7 @@ namespace OpenSim.Region.Framework.Scenes
             }
         }
 
-        private void WriteXml(XmlWriter writer)
-        {
-            writer.WriteStartElement(String.Empty, "TerrainMap", String.Empty);
-            ToXml(writer);
-            writer.WriteEndElement();
-        }
-
+        // ITerrainChannel.LoadFromXmlString()
         public void LoadFromXmlString(string data)
         {
             StringReader sr = new StringReader(data);
@@ -207,12 +204,124 @@ namespace OpenSim.Region.Framework.Scenes
             sr.Close();
         }
 
+        // ITerrainChannel.Merge
+        public void Merge(ITerrainChannel newTerrain, Vector3 displacement, float radianRotation, Vector2 rotationDisplacement)
+        {
+            m_log.DebugFormat("{0} Merge. inSize=<{1},{2}>, disp={3}, rot={4}, rotDisp={5}, outSize=<{6},{7}>", LogHeader,
+                                        newTerrain.Width, newTerrain.Height,
+                                        displacement, radianRotation, rotationDisplacement,
+                                        m_terrainData.SizeX, m_terrainData.SizeY);
+            for (int xx = 0; xx < newTerrain.Width; xx++)
+            {
+                for (int yy = 0; yy < newTerrain.Height; yy++)
+                {
+                    int dispX = (int)displacement.X;
+                    int dispY = (int)displacement.Y;
+                    float newHeight = (float)newTerrain[xx, yy] + displacement.Z;
+                    if (radianRotation == 0)
+                    {
+                        // If no rotation, place the new height in the specified location
+                        dispX += xx;
+                        dispY += yy;
+                        if (dispX >= 0 && dispX < m_terrainData.SizeX && dispY >= 0 && dispY < m_terrainData.SizeY)
+                        {
+                            m_terrainData[dispX, dispY] = newHeight;
+                        }
+                    }
+                    else
+                    {
+                        // If rotating, we have to smooth the result because the conversion
+                        //    to ints will mean heightmap entries will not get changed
+                        // First compute the rotation location for the new height.
+                        dispX += (int)(rotationDisplacement.X
+                            + ((float)xx - rotationDisplacement.X) * Math.Cos(radianRotation)
+                            - ((float)yy - rotationDisplacement.Y) * Math.Sin(radianRotation) );
+
+                        dispY += (int)(rotationDisplacement.Y
+                            + ((float)xx - rotationDisplacement.X) * Math.Sin(radianRotation)
+                            + ((float)yy - rotationDisplacement.Y) * Math.Cos(radianRotation) );
+
+                        if (dispX >= 0 && dispX < m_terrainData.SizeX && dispY >= 0 && dispY < m_terrainData.SizeY)
+                        {
+                            float oldHeight = m_terrainData[dispX, dispY];
+                            // Smooth the heights around this location if the old height is far from this one
+                            for (int sxx = dispX - 2; sxx < dispX + 2; sxx++)
+                            {
+                                for (int syy = dispY - 2; syy < dispY + 2; syy++)
+                                {
+                                    if (sxx >= 0 && sxx < m_terrainData.SizeX && syy >= 0 && syy < m_terrainData.SizeY)
+                                    {
+                                        if (sxx == dispX && syy == dispY)
+                                        {
+                                            // Set height for the exact rotated point
+                                            m_terrainData[dispX, dispY] = newHeight;
+                                        }
+                                        else
+                                        {
+                                            if (Math.Abs(m_terrainData[sxx, syy] - newHeight) > 1f)
+                                            {
+                                                // If the adjacent height is far off, force it to this height
+                                                m_terrainData[sxx, syy] = newHeight;
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+
+                        if (dispX >= 0 && dispX < m_terrainData.SizeX && dispY >= 0 && dispY < m_terrainData.SizeY)
+                        {
+                            m_terrainData[dispX, dispY] = (float)newTerrain[xx, yy];
+                        }
+                    }
+                }
+            }
+        }
+
+        #endregion
+
+        public TerrainChannel Copy()
+        {
+            TerrainChannel copy = new TerrainChannel();
+            copy.m_terrainData = m_terrainData.Clone();
+            return copy;
+        }
+
+        private void WriteXml(XmlWriter writer)
+        {
+            if (Width == Constants.RegionSize && Height == Constants.RegionSize)
+            {
+                // Downward compatibility for legacy region terrain maps.
+                // If region is exactly legacy size, return the old format XML.
+                writer.WriteStartElement(String.Empty, "TerrainMap", String.Empty);
+                ToXml(writer);
+                writer.WriteEndElement();
+            }
+            else
+            {
+                // New format XML that includes width and length.
+                writer.WriteStartElement(String.Empty, "TerrainMap2", String.Empty);
+                ToXml2(writer);
+                writer.WriteEndElement();
+            }
+        }
+
         private void ReadXml(XmlReader reader)
         {
-            reader.ReadStartElement("TerrainMap");
-            FromXml(reader);
+            // Check the first element. If legacy element, use the legacy reader.
+            if (reader.IsStartElement("TerrainMap"))
+            {
+                reader.ReadStartElement("TerrainMap");
+                FromXml(reader);
+            }
+            else
+            {
+                reader.ReadStartElement("TerrainMap2");
+                FromXml2(reader);
+            }
         }
 
+        // Write legacy terrain map. Presumed to be 256x256 of data encoded as floats in a byte array.
         private void ToXml(XmlWriter xmlWriter)
         {
             float[] mapData = GetFloatsSerialised();
@@ -226,12 +335,15 @@ namespace OpenSim.Region.Framework.Scenes
             serializer.Serialize(xmlWriter, buffer);
         }
 
+        // Read legacy terrain map. Presumed to be 256x256 of data encoded as floats in a byte array.
         private void FromXml(XmlReader xmlReader)
         {
             XmlSerializer serializer = new XmlSerializer(typeof(byte[]));
             byte[] dataArray = (byte[])serializer.Deserialize(xmlReader);
             int index = 0;
 
+            m_terrainData = new HeightmapTerrainData(Height, Width, (int)Constants.RegionHeight);
+            
             for (int y = 0; y < Height; y++)
             {
                 for (int x = 0; x < Width; x++)
@@ -244,35 +356,63 @@ namespace OpenSim.Region.Framework.Scenes
             }
         }
 
+        private class TerrainChannelXMLPackage
+        {
+            public int Version;
+            public int SizeX;
+            public int SizeY;
+            public int SizeZ;
+            public float CompressionFactor;
+            public int[] Map;
+            public TerrainChannelXMLPackage(int pX, int pY, int pZ, float pCompressionFactor, int[] pMap)
+            {
+                Version = 1;
+                SizeX = pX;
+                SizeY = pY;
+                SizeZ = pZ;
+                CompressionFactor = pCompressionFactor;
+                Map = pMap;
+            }
+        }
+
+        // New terrain serialization format that includes the width and length.
+        private void ToXml2(XmlWriter xmlWriter)
+        {
+            TerrainChannelXMLPackage package = new TerrainChannelXMLPackage(Width, Height, Altitude, m_terrainData.CompressionFactor,
+                                            m_terrainData.GetCompressedMap());
+            XmlSerializer serializer = new XmlSerializer(typeof(TerrainChannelXMLPackage));
+            serializer.Serialize(xmlWriter, package);
+        }
+
+        // New terrain serialization format that includes the width and length.
+        private void FromXml2(XmlReader xmlReader)
+        {
+            XmlSerializer serializer = new XmlSerializer(typeof(TerrainChannelXMLPackage));
+            TerrainChannelXMLPackage package = (TerrainChannelXMLPackage)serializer.Deserialize(xmlReader);
+            m_terrainData = new HeightmapTerrainData(package.Map, package.CompressionFactor, package.SizeX, package.SizeY, package.SizeZ);
+        }
+
+        // Fill the heightmap with the center bump terrain
         private void PinHeadIsland()
         {
-            int x;
-            for (x = 0; x < Constants.RegionSize; x++)
+            for (int x = 0; x < Width; x++)
             {
-                int y;
-                for (y = 0; y < Constants.RegionSize; y++)
+                for (int y = 0; y < Height; y++)
                 {
-                    map[x, y] = TerrainUtil.PerlinNoise2D(x, y, 2, 0.125) * 10;
-                    double spherFacA = TerrainUtil.SphericalFactor(x, y, Constants.RegionSize / 2.0, Constants.RegionSize / 2.0, 50) * 0.01;
-                    double spherFacB = TerrainUtil.SphericalFactor(x, y, Constants.RegionSize / 2.0, Constants.RegionSize / 2.0, 100) * 0.001;
-                    if (map[x, y] < spherFacA)
-                        map[x, y] = spherFacA;
-                    if (map[x, y] < spherFacB)
-                        map[x, y] = spherFacB;
+                    m_terrainData[x, y] = (float)TerrainUtil.PerlinNoise2D(x, y, 2, 0.125) * 10;
+                    float spherFacA = (float)(TerrainUtil.SphericalFactor(x, y, m_terrainData.SizeX / 2.0, m_terrainData.SizeY / 2.0, 50) * 0.01d);
+                    float spherFacB = (float)(TerrainUtil.SphericalFactor(x, y, m_terrainData.SizeX / 2.0, m_terrainData.SizeY / 2.0, 100) * 0.001d);
+                    if (m_terrainData[x, y]< spherFacA)
+                        m_terrainData[x, y]= spherFacA;
+                    if (m_terrainData[x, y]< spherFacB)
+                        m_terrainData[x, y] = spherFacB;
                 }
             }
         }
 
         private void FlatLand()
         {
-            int x;
-            for (x = 0; x < Constants.RegionSize; x++)
-            {
-                int y;
-                for (y = 0; y < Constants.RegionSize; y++)
-                    map[x, y] = 21;
-            }
+            m_terrainData.ClearLand();
         }
-
     }
 }
diff --git a/OpenSim/Services/Connectors/Simulation/SimulationDataService.cs b/OpenSim/Services/Connectors/Simulation/SimulationDataService.cs
index 96c02d9..4759838 100644
--- a/OpenSim/Services/Connectors/Simulation/SimulationDataService.cs
+++ b/OpenSim/Services/Connectors/Simulation/SimulationDataService.cs
@@ -100,6 +100,11 @@ namespace OpenSim.Services.Connectors
             return m_database.LoadObjects(regionUUID);
         }
 
+        public void StoreTerrain(TerrainData terrain, UUID regionID)
+        {
+            m_database.StoreTerrain(terrain, regionID);
+        }
+
         public void StoreTerrain(double[,] terrain, UUID regionID)
         {
             m_database.StoreTerrain(terrain, regionID);
@@ -110,6 +115,11 @@ namespace OpenSim.Services.Connectors
             return m_database.LoadTerrain(regionID);
         }
 
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
+        {
+            return m_database.LoadTerrain(regionID, pSizeX, pSizeY, pSizeZ);
+        }
+
         public void StoreLandObject(ILandObject Parcel)
         {
             m_database.StoreLandObject(Parcel);
diff --git a/OpenSim/Tests/Common/Mock/MockRegionDataPlugin.cs b/OpenSim/Tests/Common/Mock/MockRegionDataPlugin.cs
index 5c1ec0b..3ab9020 100644
--- a/OpenSim/Tests/Common/Mock/MockRegionDataPlugin.cs
+++ b/OpenSim/Tests/Common/Mock/MockRegionDataPlugin.cs
@@ -69,11 +69,21 @@ namespace OpenSim.Data.Null
             m_store.StoreTerrain(terrain, regionID);
         }
 
+        public void StoreTerrain(TerrainData terrain, UUID regionID)
+        {
+            m_store.StoreTerrain(terrain, regionID);
+        }
+
         public double[,] LoadTerrain(UUID regionID)
         {
             return m_store.LoadTerrain(regionID);
         }
 
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
+        {
+            return m_store.LoadTerrain(regionID, pSizeX, pSizeY, pSizeZ);
+        }
+
         public void StoreLandObject(ILandObject Parcel)
         {
             m_store.StoreLandObject(Parcel);
@@ -159,7 +169,7 @@ namespace OpenSim.Data.Null
         protected Dictionary<UUID, SceneObjectPart> m_sceneObjectParts = new Dictionary<UUID, SceneObjectPart>();
         protected Dictionary<UUID, ICollection<TaskInventoryItem>> m_primItems 
             = new Dictionary<UUID, ICollection<TaskInventoryItem>>();
-        protected Dictionary<UUID, double[,]> m_terrains = new Dictionary<UUID, double[,]>();
+        protected Dictionary<UUID, TerrainData> m_terrains = new Dictionary<UUID, TerrainData>();
         protected Dictionary<UUID, LandData> m_landData = new Dictionary<UUID, LandData>();
         
         public void Initialise(string dbfile)
@@ -304,12 +314,17 @@ namespace OpenSim.Data.Null
             return new List<SceneObjectGroup>(objects.Values);
         }
 
-        public void StoreTerrain(double[,] ter, UUID regionID)
+        public void StoreTerrain(TerrainData ter, UUID regionID)
         {
             m_terrains[regionID] = ter;
         }
 
-        public double[,] LoadTerrain(UUID regionID)
+        public void StoreTerrain(double[,] ter, UUID regionID)
+        {
+            m_terrains[regionID] = new HeightmapTerrainData(ter);
+        }
+
+        public TerrainData LoadTerrain(UUID regionID, int pSizeX, int pSizeY, int pSizeZ)
         {
             if (m_terrains.ContainsKey(regionID))
                 return m_terrains[regionID];
@@ -317,6 +332,14 @@ namespace OpenSim.Data.Null
                 return null;
         }
 
+        public double[,] LoadTerrain(UUID regionID)
+        {
+            if (m_terrains.ContainsKey(regionID))
+                return m_terrains[regionID].GetDoubles();
+            else
+                return null;
+        }
+
         public void RemoveLandObject(UUID globalID)
         {
             if (m_landData.ContainsKey(globalID))