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diff --git a/OpenSim/Framework/TerrainData.cs b/OpenSim/Framework/TerrainData.cs
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+/*
+ * 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 OpenMetaverse;
+
+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; }
+
+        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 bool IsTainted { get; protected set; }
+        public abstract bool IsTaintedAt(int xx, int yy);
+        public abstract void ClearTaint();
+
+        // 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);
+
+        // return a special compressed representation of the heightmap in shorts
+        public abstract short[] GetCompressedMap();
+        public abstract void SetCompressedMap(short[] cmap);
+
+        public abstract TerrainData Clone();
+    }
+
+    // The terrain is stored as a blob in the database 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 shorts are X and Y dimensions
+        // The dimensions are presumed to be multiples of 16 and, more likely, multiples of 256.
+        Variable2D = 22,
+        // 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 short integers. The integer values are converted to
+    //    and from floats by TerrainCompressionFactor.
+    public class HeightmapTerrainData : TerrainData
+    {
+        // TerrainData.this[x, y]
+        public override float this[int x, int y]
+        {
+            get { return FromCompressedHeight(m_heightmap[x, y]); }
+            set {
+                short 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()
+        {
+            IsTainted = false;
+            for (int ii = 0; ii < m_taint.GetLength(0); ii++)
+                for (int jj = 0; jj < m_taint.GetLength(1); jj++)
+                    m_taint[ii, jj] = false;
+        }
+
+        public override bool IsTaintedAt(int xx, int yy)
+        {
+            return m_taint[xx / Constants.TerrainPatchSize, yy / Constants.TerrainPatchSize];
+        }
+
+        // TerrainData.GetDatabaseBlob
+        // The user wants something to store in the database.
+        public override bool GetDatabaseBlob(out int DBRevisionCode, out Array blob)
+        {
+            DBRevisionCode = (int)DBTerrainRevision.Legacy256;
+            blob = LegacyTerrainSerialization();
+            return false;
+        }
+
+        public override short[] GetCompressedMap()
+        {
+            short[] newMap = new short[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;
+
+        }
+        public override void SetCompressedMap(short[] cmap)
+        {
+            int ind = 0;
+            for (int xx = 0; xx < SizeX; xx++)
+                for (int yy = 0; yy < SizeY; yy++)
+                    m_heightmap[xx, yy] = cmap[ind++];
+        }
+
+        // TerrainData.Clone
+        public override TerrainData Clone()
+        {
+            HeightmapTerrainData ret = new HeightmapTerrainData(SizeX, SizeY, SizeZ);
+            ret.m_heightmap = (short[,])this.m_heightmap.Clone();
+            return ret;
+        }
+
+        // =============================================================
+
+        private short[,] 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 static short ToCompressedHeight(double pHeight)
+        {
+            return (short)(pHeight * Constants.TerrainCompression);
+        }
+
+        public static float FromCompressedHeight(short pHeight)
+        {
+            return ((float)pHeight) / Constants.TerrainCompression;
+        }
+
+        // To keep with the legacy theme, this can be created with the way terrain
+        //     used to passed around as.
+        public HeightmapTerrainData(double[,] pTerrain)
+        {
+            SizeX = pTerrain.GetLength(0);
+            SizeY = pTerrain.GetLength(1);
+            SizeZ = (int)Constants.RegionHeight;
+
+            m_heightmap = new short[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_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_heightmap = new short[SizeX, SizeY];
+            m_taint = new bool[SizeX / Constants.TerrainPatchSize, SizeY / Constants.TerrainPatchSize];
+            ClearTaint();
+        }
+
+        public HeightmapTerrainData(short[] cmap, int pX, int pY, int pZ) : this(pX, pY, pZ)
+        {
+            SetCompressedMap(cmap);
+        }
+
+
+        // Just create an array of doubles. Presumes the caller implicitly knows the size.
+        public Array LegacyTerrainSerialization()
+        {
+            Array ret = null;
+            using (MemoryStream str = new MemoryStream(SizeX * SizeY * sizeof(double)))
+            {
+                using (BinaryWriter bw = new BinaryWriter(str))
+                {
+                    // TODO: COMPATIBILITY - Add byte-order conversions
+                    for (int ii = 0; ii < SizeX; ii++)
+                        for (int jj = 0; jj < SizeY; jj++)
+                    {
+                        double height = this[ii, jj];
+                        if (height == 0.0)
+                            height = double.Epsilon;
+                        bw.Write(height);
+                    }
+                }
+                ret = str.ToArray();
+            }
+            return ret;
+        }
+    }
+}