diff --git a/include/osg/CollectOccludersVisitor b/include/osg/CollectOccludersVisitor
index 29455edbd..0496e6ed5 100644
--- a/include/osg/CollectOccludersVisitor
+++ b/include/osg/CollectOccludersVisitor
@@ -8,6 +8,8 @@
 #include <osg/NodeVisitor>
 #include <osg/CullStack>
 
+#include <set>
+
 namespace osg {
 
 class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::CullStack
@@ -15,6 +17,8 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
     public:
 
 
+        typedef std::set<ShadowVolumeOccluder> ShadowVolumeOccluderSet;
+
         CollectOccludersVisitor();
         virtual ~CollectOccludersVisitor();
 
@@ -37,9 +41,12 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
         void setCreateDrawablesOnOccludeNodes(bool flag) { _createDrawables=flag; }
         bool getCreateDrawablesOnOccludeNodes() const { return _createDrawables; }
 
-        void setCollectedOcculderList(const ShadowVolumeOccluderList& svol) { _occluderList = svol; }
-        ShadowVolumeOccluderList& getCollectedOccluderList() { return _occluderList; }
-        const ShadowVolumeOccluderList& getCollectedOccluderList() const { return _occluderList; }
+        void setCollectedOcculderList(const ShadowVolumeOccluderSet& svol) { _occluderSet = svol; }
+        ShadowVolumeOccluderSet& getCollectedOccluderSet() { return _occluderSet; }
+        const ShadowVolumeOccluderSet& getCollectedOccluderSet() const { return _occluderSet; }
+
+        /** remove occluded occluders for the collected occluders list.*/
+        void removeOccludedOccluders();
 
 
     protected:
@@ -66,7 +73,7 @@ class SG_EXPORT CollectOccludersVisitor : public osg::NodeVisitor, public osg::C
 
         float                       _minimumShadowOccluderVolume;
         bool                        _createDrawables;
-        ShadowVolumeOccluderList    _collectedOccluderList;
+        ShadowVolumeOccluderSet     _occluderSet;
 
 };
 
diff --git a/include/osg/Polytope b/include/osg/Polytope
index cf2c29ab3..201deef07 100644
--- a/include/osg/Polytope
+++ b/include/osg/Polytope
@@ -18,16 +18,18 @@ class SG_EXPORT Polytope
 
     public:
 
-        typedef unsigned int ClippingMask;
-        typedef std::vector<Plane> PlaneList;
-        typedef fast_back_stack<ClippingMask> MaskStack;
+        typedef unsigned int                    ClippingMask;
+        typedef std::vector<Plane>              PlaneList;
+        typedef std::vector<Vec3>               VertexList;
+        typedef fast_back_stack<ClippingMask>   MaskStack;
 
         inline Polytope() {setupMask();}
 
         inline Polytope(const Polytope& cv) : 
             _maskStack(cv._maskStack),
             _resultMask(cv._resultMask),
-            _planeList(cv._planeList) {}
+            _planeList(cv._planeList),
+            _referenceVertexList(cv._referenceVertexList) {}
         
         inline Polytope(const PlaneList& pl) : _planeList(pl) {setupMask();}
 
@@ -41,6 +43,7 @@ class SG_EXPORT Polytope
             _maskStack = cv._maskStack;
             _resultMask = cv._resultMask;
             _planeList = cv._planeList;
+            _referenceVertexList = cv._referenceVertexList;
             return *this;
         }
         
@@ -77,6 +80,14 @@ class SG_EXPORT Polytope
 
         inline const PlaneList& getPlaneList() const { return _planeList; }
 
+
+        inline void setReferenceVertexList(VertexList& vertices) { _referenceVertexList=vertices; }
+
+        inline VertexList& getReferenceVertexList() { return _referenceVertexList; }
+        
+        inline const VertexList& getReferenceVertexList() const { return _referenceVertexList; }
+
+
         inline void setupMask()
         {
             _resultMask = 0;
@@ -312,6 +323,7 @@ class SG_EXPORT Polytope
         MaskStack                           _maskStack;
         ClippingMask                        _resultMask;
         PlaneList                           _planeList;
+        VertexList                          _referenceVertexList;
 
 };
 
diff --git a/include/osg/ShadowVolumeOccluder b/include/osg/ShadowVolumeOccluder
index 6aa213090..ad59fcf06 100644
--- a/include/osg/ShadowVolumeOccluder
+++ b/include/osg/ShadowVolumeOccluder
@@ -33,6 +33,8 @@ class SG_EXPORT ShadowVolumeOccluder
             _volume(0.0f) {}
 
 
+        bool operator < (const ShadowVolumeOccluder& svo) const { return getVolume()>svo.getVolume(); } // not greater volume first. 
+
         /** compute the shadow volume occluder. */
         bool computeOccluder(const NodePath& nodePath,const ConvexPlanerOccluder& occluder,CullStack& cullStack,bool createDrawables=false);
         
@@ -86,7 +88,7 @@ class SG_EXPORT ShadowVolumeOccluder
         }
         
 
-    protected:
+//    protected:
 
         float                   _volume;
         NodePath                _nodePath;
diff --git a/src/osg/CollectOccludersVisitor.cpp b/src/osg/CollectOccludersVisitor.cpp
index 787198c38..846386c64 100644
--- a/src/osg/CollectOccludersVisitor.cpp
+++ b/src/osg/CollectOccludersVisitor.cpp
@@ -5,6 +5,8 @@
 #include <osg/OccluderNode>
 #include <osg/Projection>
 
+#include <algorithm>
+
 using namespace osg;
 
 CollectOccludersVisitor::CollectOccludersVisitor()
@@ -137,7 +139,7 @@ void CollectOccludersVisitor::apply(osg::OccluderNode& node)
             {
                 // need to test occluder against view frustum.
                 //std::cout << "    adding in Occluder"<<std::endl;
-                _occluderList.push_back(svo);
+                _occluderSet.insert(svo);
             }
             else
             {
@@ -155,4 +157,41 @@ void CollectOccludersVisitor::apply(osg::OccluderNode& node)
     popOccludersCurrentMask(_nodePath);
 }
 
+void CollectOccludersVisitor::removeOccludedOccluders()
+{
+    if (_occluderSet.empty()) return;
+        
+    ShadowVolumeOccluderSet::iterator occludeeItr=_occluderSet.begin();
+    
+    // skip the first element as this can't be occluded by anything else.
+    occludeeItr++;
 
+    // step through the rest of the occluders, remove occluders which are themselves occluded.
+    for(;
+        occludeeItr!=_occluderSet.end();
+        ++occludeeItr)
+    {
+        
+        // search for any occluders that occlude the current occluder,
+        // we only need to test any occluder near the front of the set since
+        // you can't be occluder by something smaller than you.
+        const ShadowVolumeOccluder& occludee = *occludeeItr;
+        for(ShadowVolumeOccluderSet::iterator occluderItr=_occluderSet.begin();
+            occluderItr!=occludeeItr;
+            ++occluderItr)
+        {
+            // cast away constness of the std::set element since ShadowVolumeOccluder::contains() is non const,
+            // and the std::set is a const, just for the invariance of the operator <!! Ahhhhh. oh well the below
+            // should be robust since contains won't change the getVolume which is used by the operator <.  Honest,  :-)
+            ShadowVolumeOccluder* occluder = const_cast<ShadowVolumeOccluder*>(&(*occluderItr));
+            if (occluder->contains(occludee._occluderVolume.getReferenceVertexList()))
+            {
+                // erase occluder from set.
+                // take a copy of the iterator then rewind it one element so to prevent invalidating the occludeeItr.
+                ShadowVolumeOccluderSet::iterator eraseItr = occludeeItr--;
+                _occluderSet.erase(eraseItr);
+                break;
+            }
+        }
+    }
+}
diff --git a/src/osg/ShadowVolumeOccluder.cpp b/src/osg/ShadowVolumeOccluder.cpp
index 5006eb451..4688db293 100644
--- a/src/osg/ShadowVolumeOccluder.cpp
+++ b/src/osg/ShadowVolumeOccluder.cpp
@@ -14,8 +14,8 @@ typedef std::vector<Point>      PointList;
 typedef std::vector<Vec3>       VertexList;
 
 
-// convert a vector for Vec3 into a vector of Point's.
-void convert(const VertexList& in,PointList& out)
+// copyVertexListToPointList a vector for Vec3 into a vector of Point's.
+void copyVertexListToPointList(const VertexList& in,PointList& out)
 {
     out.reserve(in.size());
     for(VertexList::const_iterator itr=in.begin();
@@ -26,6 +26,17 @@ void convert(const VertexList& in,PointList& out)
     }
 }
 
+void copyPointListToVertexList(const PointList& in,VertexList& out)
+{
+    out.reserve(in.size());
+    for(PointList::const_iterator itr=in.begin();
+        itr!=in.end();
+        ++itr)
+    {
+        out.push_back(itr->second);
+    }
+}
+
 // clip the convex hull 'in' to plane to generate a clipped convex hull 'out'
 // return true if points remain after clipping.
 unsigned int clip(const Plane& plane,const PointList& in, PointList& out,unsigned int planeMask)
@@ -74,7 +85,7 @@ unsigned int clip(const Plane& plane,const PointList& in, PointList& out,unsigne
 unsigned int clip(const Polytope::PlaneList& planeList,const VertexList& vin,PointList& out)
 {
     PointList in;
-    convert(vin,in);
+    copyVertexListToPointList(vin,in);
     
     unsigned int planeMask = 0x1;
     for(Polytope::PlaneList::const_iterator itr=planeList.begin();
@@ -138,22 +149,6 @@ Plane computeFrontPlane(const PointList& front)
     return Plane(front[2].second,front[1].second,front[0].second);
 }
 
-
-// // compute the volume of tetrahedron
-// inline float computeVolume(const osg::Vec3& a,const osg::Vec3& b,const osg::Vec3& c,const osg::Vec3& d)
-// {
-//     return fabs(((b-c)^(a-b))*(d-b));
-// }
-// 
-// // compute the volume of prism.
-// inline float computeVolume(const osg::Vec3& f1,const osg::Vec3& f2,const osg::Vec3& f3,
-//                            const osg::Vec3& b1,const osg::Vec3& b2,const osg::Vec3& b3)
-// {
-//     return computeVolume(f1,f2,f3,b1)+
-//            computeVolume(b1,b2,b3,f2)+
-//            computeVolume(b1,b3,f2,f3);
-// }
-
 // compute the volume between the front and back polygons of the occluder/hole.
 float computePolytopeVolume(const PointList& front, const PointList& back)
 {
@@ -275,6 +270,10 @@ bool ShadowVolumeOccluder::computeOccluder(const NodePath& nodePath,const Convex
         // move the occlude points into projection space.
         transform(points,MV);
 
+        // use the points on the front plane as reference vertices on the _occluderVolume
+        // so that the vertices can later by used to test for occlusion of the occluder itself.
+        copyPointListToVertexList(points,_occluderVolume.getReferenceVertexList());
+
         // create the front face of the occluder
         Plane occludePlane = computeFrontPlane(points);
         _occluderVolume.add(occludePlane);
@@ -331,6 +330,10 @@ bool ShadowVolumeOccluder::computeOccluder(const NodePath& nodePath,const Convex
                 // move the occlude points into projection space.
                 transform(points,MV);
 
+                // use the points on the front plane as reference vertices on the _occluderVolume
+                // so that the vertices can later by used to test for occlusion of the occluder itself.
+                copyPointListToVertexList(points,polytope.getReferenceVertexList());
+
                 // create the front face of the occluder
                 Plane occludePlane = computeFrontPlane(points);
 
diff --git a/src/osgUtil/SceneView.cpp b/src/osgUtil/SceneView.cpp
index dd37dbbfd..bef5e32ab 100644
--- a/src/osgUtil/SceneView.cpp
+++ b/src/osgUtil/SceneView.cpp
@@ -341,9 +341,14 @@ void SceneView::cullStage(osg::Matrix* projection,osg::Matrix* modelview,osgUtil
         cov.popProjectionMatrix();
         cov.popViewport();
         
-        //std::cout << "finished searching for occluder"<<std::endl;
+        // sort the occluder from largest occluder volume to smallest.
+        cov.removeOccludedOccluders();
         
-        cullVisitor->setOccluderList(cov.getCollectedOccluderList());
+        
+        //std::cout << "finished searching for occluder"<<std::endl;
+           
+        cullVisitor->getOccluderList().clear();
+        std::copy(cov.getCollectedOccluderSet().begin(),cov.getCollectedOccluderSet().end(), std::back_insert_iterator<CullStack::OccluderList>(cullVisitor->getOccluderList()));
     }