diff --git a/include/osgSim/OverlayNode b/include/osgSim/OverlayNode
index 42794f590..1c9c8132d 100644
--- a/include/osgSim/OverlayNode
+++ b/include/osgSim/OverlayNode
@@ -71,6 +71,15 @@ class OSGSIM_EXPORT OverlayNode : public osg::Group
         /** Get whether the OverlayNode should update the overlay texture on every frame.*/
         bool getContinuousUpdate() const { return _continuousUpdate; }
 
+        /** Set the base height that the overlay subgraph will be projected down to.
+          * Normally you'll set this to just below ground level, if you set it too high
+          * then the overlay texture can end up being clipped in certain viewing directions,
+          * while if its too low then there will be a limit to how close you can get to the
+          * terrain before pixaltion becomes an issue.*/
+        void setOverlayBaseHeight(double baseHeight) { _overlayBaseHeight = baseHeight; }
+
+        /** Get the base height that the overlay subgraph will be projected down to.*/
+        double getOverlayBaseHeight() const { return _overlayBaseHeight; }
 
         /** Set the clear color to use when rendering the overlay subgraph.*/
         void setOverlayClearColor(const osg::Vec4& color) { _overlayClearColor = _overlayClearColor; }
@@ -140,6 +149,7 @@ class OSGSIM_EXPORT OverlayNode : public osg::Group
         osg::Vec4                       _overlayClearColor;
 
         bool                            _continuousUpdate;
+        double                          _overlayBaseHeight;
         bool                            _updateCamera;
 
     private:
diff --git a/src/osgSim/OverlayNode.cpp b/src/osgSim/OverlayNode.cpp
index 3240d2507..e1d6142c1 100644
--- a/src/osgSim/OverlayNode.cpp
+++ b/src/osgSim/OverlayNode.cpp
@@ -561,6 +561,7 @@ OverlayNode::OverlayNode(OverlayTechnique technique):
     _textureSizeHint(1024),
     _overlayClearColor(0.0f,0.0f,0.0f,0.0f),
     _continuousUpdate(false),
+    _overlayBaseHeight(-100.0),
     _updateCamera(false)
 {
     setNumChildrenRequiringUpdateTraversal(1);
@@ -575,7 +576,8 @@ OverlayNode::OverlayNode(const OverlayNode& copy, const osg::CopyOp& copyop):
     _textureUnit(copy._textureUnit),
     _textureSizeHint(copy._textureSizeHint),
     _overlayClearColor(copy._overlayClearColor),
-    _continuousUpdate(copy._continuousUpdate)
+    _continuousUpdate(copy._continuousUpdate),
+    _overlayBaseHeight(copy._overlayBaseHeight)
 {
     setNumChildrenRequiringUpdateTraversal(getNumChildrenRequiringUpdateTraversal()+1);            
     init();
@@ -1027,13 +1029,12 @@ void OverlayNode::traverse_VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY(osg::NodeVis
         
         if (em)
         {
-            double minHeight = -1000.0;
-            overlayPolytope.insertVertex(osg::Vec3d(0.0,0.0,0.0), em, minHeight);
+            overlayPolytope.insertVertex(osg::Vec3d(0.0,0.0,0.0), em, _overlayBaseHeight);
         }
         else
         {
             double minHeight = -1000.0;
-            overlayPolytope.projectDowntoBase(osg::Vec3d(0.0,0.0,1.0), minHeight);
+            overlayPolytope.projectDowntoBase(osg::Vec3d(0.0,0.0,1.0), _overlayBaseHeight);
         }