diff --git a/include/osgTerrain/Terrain b/include/osgTerrain/Terrain
index 011e43a38..5cf7e448d 100644
--- a/include/osgTerrain/Terrain
+++ b/include/osgTerrain/Terrain
@@ -37,24 +37,14 @@ class OSGTERRAIN_EXPORT Terrain : public osg::CoordinateSystemNode
         
         /** Set the sample ratio hint that TerrainTile should use when building geometry.
           * Defaults to 1.0, which means use all original sample points.*/
-        void setSampleRatio(float ratio) 
-        {
-            if (_sampleRatio == ratio) return;
-            _sampleRatio  = ratio;
-            dirtyRegisteredTiles();
-        }
+        void setSampleRatio(float ratio);
 
         /** Get the sample ratio hint.*/
         float getSampleRatio() const { return _sampleRatio; }
 
 
         /** Set the vertical scale hint.*/
-        void setVerticalScale(float scale) 
-        {
-            if (_verticalScale == scale) return;
-            _verticalScale = scale;
-            dirtyRegisteredTiles();
-        }
+        void setVerticalScale(float scale);
 
         /** Get the vertical scale hint.*/
         float getVerticalScale() const { return _verticalScale; }
@@ -64,12 +54,7 @@ class OSGTERRAIN_EXPORT Terrain : public osg::CoordinateSystemNode
           * Note, the Terrain::BlendingPolicy value only sets the value for the TerrainTiles it encloses for the
           * TerrainTile's that have their policy set to INHERIT.   INHERIT is the default BlendingPolicy for both
           * Terrain and TerrainTile, and if both are left to INERHIT then the policy used is ENABLE_BLENDING_WHEN_ALPHA_PRESENT. */
-        void setBlendingPolicy(TerrainTile::BlendingPolicy policy)
-        {
-            if (_blendingPolicy == policy) return;
-            _blendingPolicy = policy;
-            dirtyRegisteredTiles();
-        }
+        void setBlendingPolicy(TerrainTile::BlendingPolicy policy);
 
         /** Get the default policy to use when deciding whether to enable/disable blending and use of transparent bin.*/
         TerrainTile::BlendingPolicy getBlendingPolicy() const { return _blendingPolicy; }
@@ -99,7 +84,7 @@ class OSGTERRAIN_EXPORT Terrain : public osg::CoordinateSystemNode
         
         friend class TerrainTile;
         
-        void dirtyRegisteredTiles();
+        void dirtyRegisteredTiles(int dirtyMask = TerrainTile::ALL_DIRTY);
 
         void registerTerrainTile(TerrainTile* tile);
         void unregisterTerrainTile(TerrainTile* tile);
diff --git a/src/osgTerrain/Terrain.cpp b/src/osgTerrain/Terrain.cpp
index 90047f04b..f5ae4257b 100644
--- a/src/osgTerrain/Terrain.cpp
+++ b/src/osgTerrain/Terrain.cpp
@@ -50,11 +50,32 @@ Terrain::~Terrain()
     {
         const_cast<TerrainTile*>(*itr)->_terrain = 0;
     }
-    
+
     _terrainTileSet.clear();
     _terrainTileMap.clear();
 }
 
+void Terrain::setSampleRatio(float ratio)
+{
+    if (_sampleRatio == ratio) return;
+    _sampleRatio  = ratio;
+    dirtyRegisteredTiles();
+}
+
+void Terrain::setVerticalScale(float scale)
+{
+    if (_verticalScale == scale) return;
+    _verticalScale = scale;
+    dirtyRegisteredTiles();
+}
+
+void Terrain::setBlendingPolicy(TerrainTile::BlendingPolicy policy)
+{
+    if (_blendingPolicy == policy) return;
+    _blendingPolicy = policy;
+    dirtyRegisteredTiles();
+}
+
 void Terrain::traverse(osg::NodeVisitor& nv)
 {
     if (nv.getVisitorType()==osg::NodeVisitor::UPDATE_VISITOR)
@@ -107,7 +128,7 @@ const TerrainTile* Terrain::getTile(const TileID& tileID) const
     return itr->second;
 }
 
-void Terrain::dirtyRegisteredTiles()
+void Terrain::dirtyRegisteredTiles(int dirtyMask)
 {
     OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
 
@@ -115,7 +136,7 @@ void Terrain::dirtyRegisteredTiles()
         itr != _terrainTileSet.end();
         ++itr)
     {
-        (const_cast<TerrainTile*>(*itr))->setDirty(true);
+        (const_cast<TerrainTile*>(*itr))->setDirtyMask(dirtyMask);
     }
 }