From Brad Christiansen and Robert Osfield, "I have added the new function as suggested. The change was made against trunk from an hour or so ago. I haven't tested the performance yet (and probably won't get a chance till next week) but I have checked my terrains still work. I defaulted the equalization to off as I thought this was best until we can look into why there is the performance hit.

", note from Robert, tweaked the names and enabled the code path.

include/osgTerrain/Terrain

@@ -49,6 +49,14 @@ class OSGTERRAIN_EXPORT Terrain : public osg::CoordinateSystemNode
         /** Get the vertical scale hint.*/
         float getVerticalScale() const { return _verticalScale; }
 
+        /** If set to true the boundaries between adjacent tiles should be equalized.
+          * Note, it is only possible to equalizae boundaries when the TerrainTile's contain properly assigned TileID's,
+          * databases built with VirtualPlanetBuilder-0.9.11 and older do not set the TileID, so databases must be
+          * built with later versions of VirtualPlanetBuilder to take advatange of boundary equalization. */
+        void setEqualizeBoundaries(bool equalizeBoundaries);
+
+        /** If true the boundaries between adjacent tiles will be equalized. */
+        bool getEqualizeBoundaries() const { return _equalizeBoundaries; }
 
         /** Set the default policy to use when deciding whether to enable/disable blending and use of transparent bin.
           * Note, the Terrain::BlendingPolicy value only sets the value for the TerrainTiles it encloses for the
@@ -95,6 +103,7 @@ class OSGTERRAIN_EXPORT Terrain : public osg::CoordinateSystemNode
         float                               _sampleRatio;
         float                               _verticalScale;
         TerrainTile::BlendingPolicy         _blendingPolicy;
+        bool                                _equalizeBoundaries;
 
         mutable OpenThreads::Mutex          _mutex;
         TerrainTileSet                      _terrainTileSet;

src/osgTerrain/GeometryTechnique.cpp

@@ -29,8 +29,6 @@
 
 using namespace osgTerrain;
 
-#define NEW_COORD_CODE
-
 GeometryTechnique::GeometryTechnique()
 {
     setFilterBias(0);
@@ -880,8 +878,7 @@ void GeometryTechnique::generateGeometry(BufferData& buffer, Locator* masterLoca
     //
     VNG.populateCenter(elevationLayer, layerToTexCoordMap);
 
-#if 1
+    if (terrain && terrain->getEqualizeBoundaries())
-    if (terrain)
     {
         TileID tileID = _terrainTile->getTileID();
 
@@ -997,7 +994,6 @@ void GeometryTechnique::generateGeometry(BufferData& buffer, Locator* masterLoca
         }
 #endif
     }
-#endif
 
 
     osg::ref_ptr<osg::Vec3Array> skirtVectors = new osg::Vec3Array((*VNG._normals));

src/osgTerrain/Terrain.cpp

@@ -25,7 +25,8 @@ using namespace osgTerrain;
 Terrain::Terrain():
     _sampleRatio(1.0),
     _verticalScale(1.0),
-    _blendingPolicy(TerrainTile::INHERIT)
+    _blendingPolicy(TerrainTile::INHERIT),
+    _equalizeBoundaries(false)
 {
     setNumChildrenRequiringUpdateTraversal(1);
     _terrainTechnique = new GeometryTechnique;
@@ -36,6 +37,7 @@ Terrain::Terrain(const Terrain& ts, const osg::CopyOp& copyop):
     _sampleRatio(ts._sampleRatio),
     _verticalScale(ts._verticalScale),
     _blendingPolicy(ts._blendingPolicy),
+    _equalizeBoundaries(ts._equalizeBoundaries),
     _terrainTechnique(ts._terrainTechnique)
 {
     setNumChildrenRequiringUpdateTraversal(getNumChildrenRequiringUpdateTraversal()+1);
@@ -71,6 +73,13 @@ void Terrain::setVerticalScale(float scale)
     dirtyRegisteredTiles();
 }
 
+void Terrain::setEqualizeBoundaries(bool equalizeBoundaries)
+{
+  if(_equalizeBoundaries == equalizeBoundaries) return;
+  _equalizeBoundaries = equalizeBoundaries;
+  dirtyRegisteredTiles();
+}
+
 void Terrain::setBlendingPolicy(TerrainTile::BlendingPolicy policy)
 {
     if (_blendingPolicy == policy) return;