7 files changed, 675 insertions, 209 deletions

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();
         }
-
     }
 }