diff --git a/include/osg/Drawable b/include/osg/Drawable
index 82bd235fd..cf1205f5a 100644
--- a/include/osg/Drawable
+++ b/include/osg/Drawable
@@ -247,23 +247,38 @@ class SG_EXPORT Drawable : public Object
         virtual void compile(State& state) const;
 
 
-        struct UpdateCallback : public virtual osg::Referenced
+        struct UpdateCallback : public virtual osg::Object
         {
-                /** do customized app code.*/
-                virtual void update(osg::NodeVisitor *visitor, osg::Drawable* drawable) = 0;
+            UpdateCallback() {}
+
+            UpdateCallback(const UpdateCallback&,const CopyOp&) {}
+
+            META_Object(osg,UpdateCallback)
+
+            /** do customized update code.*/
+            virtual void update(osg::NodeVisitor*, osg::Drawable*) {}
         };
         
-        /** Set the UpdateCallback which allows users to attach customize the undating of an object during the app traversal.*/
+        /** Set the UpdateCallback which allows users to attach customize the undating of an object during the update traversal.*/
         void setUpdateCallback(UpdateCallback* ac);
         
         /** Get the non const UpdateCallback.*/
         UpdateCallback* getUpdateCallback() { return _updateCallback.get(); }
 
+        /** Get the const UpdateCallback.*/
+        const UpdateCallback* getUpdateCallback() const { return _updateCallback.get(); }
+        
 
-        struct CullCallback : public virtual osg::Referenced
+        struct CullCallback : public virtual osg::Object
         {
-                /** do customized cull code.*/
-                virtual bool cull(osg::NodeVisitor *visitor, osg::Drawable* drawable, osg::State *state=NULL) const = 0;
+            CullCallback() {}
+
+            CullCallback(const CullCallback&,const CopyOp&) {}
+
+            META_Object(osg,CullCallback)
+
+            /** do customized cull code, return true if drawable should be culled.*/
+            virtual bool cull(osg::NodeVisitor*, osg::Drawable*, osg::State*) const { return false; }
         };
 
         /** Set the CullCallback which allows users to attach customize the culling of Drawable during the cull traversal.*/
@@ -274,6 +289,8 @@ class SG_EXPORT Drawable : public Object
         
         /** Get the const CullCallback.*/
         const CullCallback* getCullCallback() const { return _cullCallback.get(); }
+        
+        
 
 
         /** Callback attached to an Drawable which allows the users to customize the drawing of an exist Drawable object.
@@ -281,10 +298,16 @@ class SG_EXPORT Drawable : public Object
           * the user intends to decorate the exist draw code then simple call the drawable->drawImplementation() from
           * with the callbacks drawImplementation() method.  This allows the users to do both pre and post callbacks
           * without fuss and can even diable the inner draw in required.*/
-        struct DrawCallback : public virtual osg::Referenced
+        struct DrawCallback : public virtual osg::Object
         {
+            DrawCallback() {}
+
+            DrawCallback(const DrawCallback&,const CopyOp&) {}
+
+            META_Object(osg,DrawCallback)
+
             /** do customized draw code.*/
-            virtual void drawImplementation(State& state,const osg::Drawable* drawable) const = 0;
+            virtual void drawImplementation(State&,const osg::Drawable*) const {}
         };
 
         /** Set the DrawCallback which allows users to attach customize the drawing of existing Drawable object.*/
@@ -684,6 +707,44 @@ inline void Drawable::draw(State& state) const
         drawImplementation(state);
 };
 
+/** Drawable CullCallback for adding cluster culling to cull back facing
+  * drawables.*/
+class SG_EXPORT ClusterCullingCallback : public Drawable::CullCallback
+{
+    public:
+
+        ClusterCullingCallback();
+        ClusterCullingCallback(const ClusterCullingCallback& ccc,const CopyOp& copyop);
+        ClusterCullingCallback(const osg::Vec3& controlPoint, const osg::Vec3& normal, float deviation);
+        ClusterCullingCallback(const osg::Drawable* drawable);
+
+        META_Object(osg,ClusterCullingCallback)
+
+        /** compute the control point, normal and deviation from the contents of the drawable.*/
+        void computeFrom(const osg::Drawable* drawable);
+
+        void set(const osg::Vec3& controlPoint, const osg::Vec3& normal, float deviation);
+
+        void setControlPoint(const osg::Vec3& controlPoint) { _controlPoint = controlPoint; }
+        const osg::Vec3& getControlPoint() const { return _controlPoint; }
+
+        void setNormal(const osg::Vec3& normal) { _normal = normal; }
+        const osg::Vec3& getNormal() const { return _normal; }
+
+        void setDeviation(float deviation) { _deviation = deviation; }
+        float getDeviation() const { return _deviation; }
+
+        virtual bool cull(osg::NodeVisitor*, osg::Drawable*, osg::State*) const;
+
+    protected:
+
+        virtual ~ClusterCullingCallback() {}
+
+        osg::Vec3 _controlPoint;
+        osg::Vec3 _normal;
+        float _deviation;
+};
+
 
 }
 
diff --git a/src/osg/Drawable.cpp b/src/osg/Drawable.cpp
index b9f04d8d8..dfe671cc0 100644
--- a/src/osg/Drawable.cpp
+++ b/src/osg/Drawable.cpp
@@ -20,6 +20,7 @@
 #include <osg/Node>
 #include <osg/GLExtensions>
 #include <osg/Timer>
+#include <osg/TriangleFunctor>
 
 #include <algorithm>
 #include <map>
@@ -891,3 +892,83 @@ void Drawable::Extensions::glGetOcclusionQueryuiv( GLuint id, GLenum pname, GLui
         osg::notify(osg::WARN)<<"Error: glGetOcclusionQueryuiv not supported by OpenGL driver"<<std::endl;
     }    
 }
+
+///////////////////////////////////////////////////////////////////////////////////////////
+//
+//  Cluster culling callback
+//
+
+ClusterCullingCallback::ClusterCullingCallback():
+    _deviation(-1.0f)
+{
+}
+
+ClusterCullingCallback::ClusterCullingCallback(const ClusterCullingCallback& ccc,const CopyOp& copyop):
+    Drawable::CullCallback(ccc,copyop),
+    _controlPoint(ccc._controlPoint),_normal(ccc._normal),_deviation(ccc._deviation)
+{
+}
+
+ClusterCullingCallback::ClusterCullingCallback(const osg::Vec3& controlPoint, const osg::Vec3& normal, float deviation):
+    _controlPoint(controlPoint),_normal(normal), _deviation(deviation)
+{
+}
+
+ClusterCullingCallback::ClusterCullingCallback(const osg::Drawable* drawable)
+{
+    computeFrom(drawable);
+}
+
+struct CollectNormalsFunctor
+{
+
+    CollectNormalsFunctor():
+         _x(0.0),_y(0.0),_z(0) {}
+
+    inline void operator() ( const osg::Vec3 &v1, const osg::Vec3 &v2, const osg::Vec3 &v3, bool)
+    {
+        // calc orientation of triangle.
+        osg::Vec3 normal = (v2-v1)^(v3-v1);
+        normal.normalize();
+
+        _normals.push_back(normal);
+        
+        _x += v1.x();
+        _y += v1.y();
+        _z += v1.z();
+        
+        _x += v2.x();
+        _y += v2.y();
+        _z += v2.z();
+        
+        _x += v3.x();
+        _y += v3.y();
+        _z += v3.z();
+
+    }
+    
+    typedef std::vector<osg::Vec3> NormalList;
+    NormalList _normals;
+    double _x,_y,_z;
+};
+
+
+
+void ClusterCullingCallback::computeFrom(const osg::Drawable* drawable)
+{
+    TriangleFunctor<CollectNormalsFunctor> stf;
+    drawable->accept(stf);
+}
+
+void ClusterCullingCallback::set(const osg::Vec3& controlPoint, const osg::Vec3& normal, float deviation)
+{
+    _controlPoint = controlPoint;
+    _normal = normal;
+    _deviation = deviation;
+}
+
+
+bool ClusterCullingCallback::cull(osg::NodeVisitor*, osg::Drawable*, osg::State*) const
+{
+    return false;
+}
diff --git a/src/osgDB/DatabasePager.cpp b/src/osgDB/DatabasePager.cpp
index 1413faf3f..2f4eb7c94 100644
--- a/src/osgDB/DatabasePager.cpp
+++ b/src/osgDB/DatabasePager.cpp
@@ -15,7 +15,7 @@ using namespace osgDB;
 
 DatabasePager::DatabasePager()
 {
-    //std::cout<<"Constructing DatabasePager()"<<std::endl;
+    //osg::notify(osg::INFO)<<"Constructing DatabasePager()"<<std::endl;
     
     _deleteRemovedSubgraphsInDatabaseThread = true;
     
@@ -178,7 +178,7 @@ public:
 
         if (drawable->getUseDisplayList() || drawable->getUseVertexBufferObjects())
         {
-            //std::cout<<"Found compilable drawable"<<std::endl;
+            //osg::notify(osg::INFO)<<"Found compilable drawable"<<std::endl;
             _dataToCompile.second.push_back(drawable);
         }
     }
@@ -189,7 +189,7 @@ public:
 
 void DatabasePager::run()
 {
-    std::cout<<"DatabasePager::run()"<<std::endl;
+    osg::notify(osg::NOTICE)<<"DatabasePager::run()"<<std::endl;
 
     // need to set the texture object manager to be able to reuse textures
     // by keeping deleted texture objects around for 10 seconds after being deleted.
@@ -206,7 +206,7 @@ void DatabasePager::run()
             _childrenToDeleteListMutex.lock();
                 if (!_childrenToDeleteList.empty())
                 {
-                    std::cout<<"In DatabasePager thread deleting "<<_childrenToDeleteList.size()<<" subgraphs"<<std::endl;
+                    osg::notify(osg::INFO)<<"In DatabasePager thread deleting "<<_childrenToDeleteList.size()<<" subgraphs"<<std::endl;
                     _childrenToDeleteList.clear();
                 }
             _childrenToDeleteListMutex.unlock();
@@ -323,7 +323,7 @@ void DatabasePager::addLoadedDataToSceneGraph(double timeStamp)
             plod->setTimeStamp(plod->getNumChildren(),timeStamp);
         } 
         group->addChild(databaseRequest->_loadedModel.get());
-        std::cout<<"merged subgraph"<<databaseRequest->_fileName<<" after "<<databaseRequest->_numOfRequests<<" requests."<<std::endl;
+        osg::notify(osg::INFO)<<"merged subgraph"<<databaseRequest->_fileName<<" after "<<databaseRequest->_numOfRequests<<" requests."<<std::endl;
 
     }
     
@@ -387,7 +387,7 @@ void DatabasePager::removeExpiredSubgraphs(double currentFrameTime)
 
     osg::NodeList childrenRemoved;
 
-    //std::cout<<"DatabasePager::removeExpiredSubgraphs("<<expiryTime<<") "<<std::endl;
+    //osg::notify(osg::INFO)<<"DatabasePager::removeExpiredSubgraphs("<<expiryTime<<") "<<std::endl;
     for(PagedLODList::iterator itr=_pagedLODList.begin();
         itr!=_pagedLODList.end();
         ++itr)
@@ -405,12 +405,12 @@ void DatabasePager::removeExpiredSubgraphs(double currentFrameTime)
         osg::PagedLOD* plod = _pagedLODList[i].get();
         if (plod->referenceCount()==1)
         {
-            //std::cout<<"    PagedLOD "<<plod<<" orphaned"<<std::endl;
+            //osg::notify(osg::INFO)<<"    PagedLOD "<<plod<<" orphaned"<<std::endl;
             _pagedLODList.erase(_pagedLODList.begin()+i);
         }
         else
         {
-            //std::cout<<"    PagedLOD "<<plod<<" refcount "<<plod->referenceCount()<<std::endl;
+            //osg::notify(osg::INFO)<<"    PagedLOD "<<plod<<" refcount "<<plod->referenceCount()<<std::endl;
         }
     }
      
@@ -505,13 +505,13 @@ void DatabasePager::compileRenderingObjects(osg::State& state, double& available
         {
             // we have StateSet's to compile
             StateSetList& sslist = dtc.first;
-            //std::cout<<"Compiling statesets"<<std::endl;
+            //osg::notify(osg::INFO)<<"Compiling statesets"<<std::endl;
             StateSetList::iterator itr=sslist.begin();
             for(;
                 itr!=sslist.end() && elapsedTime<availableTime;
                 ++itr)
             {
-                //std::cout<<"    Compiling stateset "<<(*itr).get()<<std::endl;
+                //osg::notify(osg::INFO)<<"    Compiling stateset "<<(*itr).get()<<std::endl;
                 (*itr)->compile(state);
                 elapsedTime = timer.delta_s(start_tick,timer.tick());
             }
@@ -521,14 +521,14 @@ void DatabasePager::compileRenderingObjects(osg::State& state, double& available
         if (!dtc.second.empty() && elapsedTime<availableTime)
         {
             // we have Drawable's to compile
-            //std::cout<<"Compiling drawables"<<std::endl;
+            //osg::notify(osg::INFO)<<"Compiling drawables"<<std::endl;
             DrawableList& dwlist = dtc.second;
             DrawableList::iterator itr=dwlist.begin();
             for(;
                 itr!=dwlist.end() && elapsedTime<availableTime;
                 ++itr)
             {
-                //std::cout<<"    Compiling drawable "<<(*itr).get()<<std::endl;
+                //osg::notify(osg::INFO)<<"    Compiling drawable "<<(*itr).get()<<std::endl;
                 (*itr)->compile(state);
                 elapsedTime = timer.delta_s(start_tick,timer.tick());
             }
@@ -536,7 +536,7 @@ void DatabasePager::compileRenderingObjects(osg::State& state, double& available
             dwlist.erase(dwlist.begin(),itr);
         }
         
-        //std::cout<<"Checking if compiled"<<std::endl;
+        //osg::notify(osg::INFO)<<"Checking if compiled"<<std::endl;
 
         // now check the to compile entries for all active graphics contexts
         // to make sure that all have been compiled.
@@ -552,7 +552,7 @@ void DatabasePager::compileRenderingObjects(osg::State& state, double& available
         
         if (allCompiled)
         {
-            std::cout<<"All compiled"<<std::endl;
+            osg::notify(osg::INFO)<<"All compiled"<<std::endl;
 
             // we've compile all of the current databaseRequest so we can now pop it off the
             // to compile list and place it on the merge list.
@@ -571,7 +571,7 @@ void DatabasePager::compileRenderingObjects(osg::State& state, double& available
         }
         else 
         {
-            //std::cout<<"Not all compiled"<<std::endl;
+            //osg::notify(osg::INFO)<<"Not all compiled"<<std::endl;
             databaseRequest = 0;
         }