diff --git a/examples/osgdem/DataSet.cpp b/examples/osgdem/DataSet.cpp
index cadc4f530..c8f66aa80 100644
--- a/examples/osgdem/DataSet.cpp
+++ b/examples/osgdem/DataSet.cpp
@@ -142,63 +142,10 @@ DataSet::SourceData* DataSet::SourceData::readData(Source* source)
 
 osg::BoundingBox DataSet::SourceData::getExtents(const osgTerrain::CoordinateSystem* cs) const
 {
-    if (_cs==cs) return _extents;
-    if (_cs.valid() && cs)
-    {
-        if (*_cs == *cs) return _extents;
-        
-        if (_gdalDataSet)
-        {
-
-            //std::cout<<"Projecting bounding volume for "<<_source->getFileName()<<std::endl;
-
-            osg::BoundingBox bb;
-            
-            /* -------------------------------------------------------------------- */
-            /*      Create a transformation object from the source to               */
-            /*      destination coordinate system.                                  */
-            /* -------------------------------------------------------------------- */
-            void *hTransformArg = 
-                GDALCreateGenImgProjTransformer( _gdalDataSet,_cs->getProjectionRef().c_str(),
-                                                 NULL, cs->getProjectionRef().c_str(),
-                                                 TRUE, 0.0, 1 );
-
-            if (!hTransformArg)
-            {
-                std::cout<<" failed to create transformer"<<std::endl;
-                return bb;
-            }
-        
-            double adfDstGeoTransform[6];
-            int nPixels=0, nLines=0;
-            if( GDALSuggestedWarpOutput( _gdalDataSet, 
-                                         GDALGenImgProjTransform, hTransformArg, 
-                                         adfDstGeoTransform, &nPixels, &nLines )
-                != CE_None )
-            {
-                std::cout<<" failed to create warp"<<std::endl;
-                return bb;
-            }
-
-            osg::Matrixd geoTransform( adfDstGeoTransform[1],    adfDstGeoTransform[4],    0.0,    0.0,
-                                       adfDstGeoTransform[2],    adfDstGeoTransform[5],    0.0,    0.0,
-                                       0.0,                0.0,                1.0,    0.0,
-                                       adfDstGeoTransform[0],    adfDstGeoTransform[3],    0.0,    1.0);
-
-            GDALDestroyGenImgProjTransformer( hTransformArg );
-
-            bb.expandBy( osg::Vec3(0.0,0.0,0.0)*geoTransform);
-            bb.expandBy( osg::Vec3(nPixels,nLines,0.0)*geoTransform);
-            
-            return bb;
-        }
-
-    }
-    std::cout<<"DataSet::DataSource::assuming compatible coordinates."<<std::endl;
-    return _extents;
+    return computeSpatialProperties(cs)._extents;
 }
 
-const DataSet::SpatialProperties& DataSet::SourceData::computeSpatialProperties(osgTerrain::CoordinateSystem* cs) const
+const DataSet::SpatialProperties& DataSet::SourceData::computeSpatialProperties(const osgTerrain::CoordinateSystem* cs) const
 {
     if (_cs==cs) return *this;
     if (_cs.valid() && cs)
@@ -247,7 +194,7 @@ const DataSet::SpatialProperties& DataSet::SourceData::computeSpatialProperties(
 
             sp._numValuesX = nPixels;
             sp._numValuesY = nLines;
-            sp._cs = cs;
+            sp._cs = const_cast<osgTerrain::CoordinateSystem*>(cs);
             sp._geoTransform.set( adfDstGeoTransform[1],    adfDstGeoTransform[4],  0.0,    0.0,
                                   adfDstGeoTransform[2],    adfDstGeoTransform[5],  0.0,    0.0,
                                   0.0,                      0.0,                    1.0,    0.0,
@@ -428,7 +375,8 @@ void DataSet::SourceData::readHeightField(DestinationData& destination)
 	else if (!bandSelected && bandGreen) bandSelected = bandGreen;
 	else if (!bandSelected && bandBlue) bandSelected = bandBlue;
         
-        float heightRatio = 1.0/65536;
+        //float heightRatio = 1.0/65536;
+        float heightRatio = 1.0;
 
         if (bandSelected)
         {
@@ -1906,10 +1854,19 @@ void DataSet::computeDestinationGraphFromSources(unsigned int numLevels)
         for(CompositeSource::source_iterator itr(_sourceGraph.get());itr.valid();++itr)
         {
             SourceData* sd = (*itr)->getSourceData();
-            if (sd) extents.expandBy(sd->getExtents(_coordinateSystem.get()));
+            if (sd)
+            {
+                osg::BoundingBox local_extents(sd->getExtents(_coordinateSystem.get()));
+                std::cout<<"local_extents = xMin()"<<local_extents.xMin()<<" "<<local_extents.xMax()<<std::endl;
+                std::cout<<"                yMin()"<<local_extents.yMin()<<" "<<local_extents.yMax()<<std::endl;
+                extents.expandBy(local_extents);
+            }
         }
     }
 
+    std::cout<<"extents = xMin()"<<extents.xMin()<<" "<<extents.xMax()<<std::endl;
+    std::cout<<"          yMin()"<<extents.yMin()<<" "<<extents.yMax()<<std::endl;
+
     // then create the destinate graph accordingly.
 
     unsigned int imageSize = 256;
diff --git a/examples/osgdem/DataSet.h b/examples/osgdem/DataSet.h
index ff3b63756..e4f47dd62 100644
--- a/examples/osgdem/DataSet.h
+++ b/examples/osgdem/DataSet.h
@@ -113,7 +113,7 @@ class DataSet : public osg::Referenced
             
             osg::BoundingBox getExtents(const osgTerrain::CoordinateSystem* cs) const;
             
-            const SpatialProperties& computeSpatialProperties(osgTerrain::CoordinateSystem* cs) const;
+            const SpatialProperties& computeSpatialProperties(const osgTerrain::CoordinateSystem* cs) const;
 
             bool intersects(const SpatialProperties& sp) const;
 
@@ -130,7 +130,7 @@ class DataSet : public osg::Referenced
             osg::ref_ptr<osg::Node>                     _model;
             GDALDataset*                                _gdalDataSet;
             
-            typedef std::map<osgTerrain::CoordinateSystem*,SpatialProperties> SpatialPropertiesMap;
+            typedef std::map<const osgTerrain::CoordinateSystem*,SpatialProperties> SpatialPropertiesMap;
             mutable SpatialPropertiesMap _spatialPropertiesMap;
             
             
@@ -769,8 +769,11 @@ class DataSet : public osg::Referenced
 
         void loadSources();
         
+        void setDestinationCoordinateSystem(const std::string& wellKnownText) { _coordinateSystem = new osgTerrain::CoordinateSystem(wellKnownText); }
         void setDestinationCoordinateSystem(osgTerrain::CoordinateSystem* cs) { _coordinateSystem = cs; }
+        
         void setDestinationExtents(const osg::BoundingBox& extents) { _extents = extents; }
+        
         void setDestinationGeoTransform(const osg::Matrixd& geoTransform) { _geoTransform = geoTransform; }
         
         void setDestinationTileBaseName(const std::string& basename) { _tileBasename = basename; }
diff --git a/examples/osgdem/osgdem.cpp b/examples/osgdem/osgdem.cpp
index 1c8e53975..99ab89422 100644
--- a/examples/osgdem/osgdem.cpp
+++ b/examples/osgdem/osgdem.cpp
@@ -27,10 +27,12 @@
 #include <osgFX/BumpMapping>
 
 #include <osgProducer/Viewer>
+#include <osg/Switch>
 
 #include "DataSet.h"
 
-#include <osg/Switch>
+#include <ogr_spatialref.h>
+
 
 int main( int argc, char **argv )
 {
@@ -79,6 +81,8 @@ int main( int argc, char **argv )
     {
         dataset->setDestinationExtents(osg::BoundingBox(x,y,0.0f,x+w,y+h,0.0f));
     }
+    
+    
 
     dataset->setDestinationTileBaseName("output");
     dataset->setDestinationTileExtension(".ive");
@@ -110,6 +114,25 @@ int main( int argc, char **argv )
         return 1;
     }
 
+
+    if (false)    
+    {
+        // set up the coordinate system
+        OGRSpatialReference     oSRS;
+
+        oSRS.SetProjCS( "UTM 47 (WGS84) in southern hemisphere." );
+        oSRS.SetWellKnownGeogCS( "WGS84" );
+        oSRS.SetUTM( 47, FALSE );
+
+        // get the Well Known Text string
+        char    *pszWKT = NULL;
+        oSRS.exportToWkt( &pszWKT );
+        
+        // set the destination coordinate system
+        dataset->setDestinationCoordinateSystem(pszWKT);
+    }
+
+    
     // any option left unread are converted into errors to write out later.
     arguments.reportRemainingOptionsAsUnrecognized();