diff --git a/include/osgSim/ElevationSlice b/include/osgSim/ElevationSlice
index bb7bde227..7290cf8ef 100644
--- a/include/osgSim/ElevationSlice
+++ b/include/osgSim/ElevationSlice
@@ -58,10 +58,10 @@ class OSGSIM_EXPORT ElevationSlice
           * Note, if the topmost node is a CoordinateSystemNode then the input points are assumed to be geocentric,
           * with the up vector defined by the EllipsoidModel attached to the CoordinateSystemNode.
           * If the topmost node is not a CoordinateSystemNode then a local coordinates frame is assumed, with a local up vector. */
-        void computeIntersections(osg::Node* scene);
+        void computeIntersections(osg::Node* scene, osg::Node::NodeMask traversalMask=0xffffffff);
 
         /** Compute the vertical distance between the specified scene graph and a single HAT point. .*/
-        static Vec3dList computeElevationSlice(osg::Node* scene, const osg::Vec3d& startPoint, const osg::Vec3d& endPoint);
+        static Vec3dList computeElevationSlice(osg::Node* scene, const osg::Vec3d& startPoint, const osg::Vec3d& endPoint, osg::Node::NodeMask traversalMask=0xffffffff);
         
         
         /** Clear the database cache.*/
diff --git a/include/osgSim/HeightAboveTerrain b/include/osgSim/HeightAboveTerrain
index 39b77b155..bd3f41548 100644
--- a/include/osgSim/HeightAboveTerrain
+++ b/include/osgSim/HeightAboveTerrain
@@ -62,10 +62,10 @@ class OSGSIM_EXPORT HeightAboveTerrain
           * Note, if the topmost node is a CoordinateSystemNode then the input points are assumed to be geocentric,
           * with the up vector defined by the EllipsoidModel attached to the CoordinateSystemNode.
           * If the topmost node is not a CoordinateSystemNode then a local coordinates frame is assumed, with a local up vector. */
-        void computeIntersections(osg::Node* scene);
+        void computeIntersections(osg::Node* scene, osg::Node::NodeMask traversalMask=0xffffffff);
 
         /** Compute the vertical distance between the specified scene graph and a single HAT point. .*/
-        static double computeHeightAboveTerrain(osg::Node* scene, const osg::Vec3d& point);
+        static double computeHeightAboveTerrain(osg::Node* scene, const osg::Vec3d& point, osg::Node::NodeMask traversalMask=0xffffffff);
         
         
         /** Clear the database cache.*/
diff --git a/include/osgSim/LineOfSight b/include/osgSim/LineOfSight
index e82247edc..a15c6cf0e 100644
--- a/include/osgSim/LineOfSight
+++ b/include/osgSim/LineOfSight
@@ -79,10 +79,10 @@ class OSGSIM_EXPORT LineOfSight
 
         /** Compute the LOS intersections with the specified scene graph.
           * The results are all stored in the form of Intersections list, one per LOS test.*/
-        void computeIntersections(osg::Node* scene);
+        void computeIntersections(osg::Node* scene, osg::Node::NodeMask traversalMask=0xffffffff);
 
         /** Compute the intersection between the specified scene graph and a single LOS start,end pair. Returns an IntersectionList, of all the points intersected.*/
-        static Intersections computeIntersections(osg::Node* scene, const osg::Vec3d& start, const osg::Vec3d& end);
+        static Intersections computeIntersections(osg::Node* scene, const osg::Vec3d& start, const osg::Vec3d& end, osg::Node::NodeMask traversalMask=0xffffffff);
         
         
         /** Clear the database cache.*/
diff --git a/src/osgSim/ElevationSlice.cpp b/src/osgSim/ElevationSlice.cpp
index f9b56624d..c796517f3 100644
--- a/src/osgSim/ElevationSlice.cpp
+++ b/src/osgSim/ElevationSlice.cpp
@@ -1162,7 +1162,7 @@ ElevationSlice::ElevationSlice()
     setDatabaseCacheReadCallback(new DatabaseCacheReadCallback);
 }
 
-void ElevationSlice::computeIntersections(osg::Node* scene)
+void ElevationSlice::computeIntersections(osg::Node* scene, osg::Node::NodeMask traversalMask)
 {
     osg::CoordinateSystemNode* csn = dynamic_cast<osg::CoordinateSystemNode*>(scene);
     osg::EllipsoidModel* em = csn ? csn->getEllipsoidModel() : 0;
@@ -1231,6 +1231,7 @@ void ElevationSlice::computeIntersections(osg::Node* scene)
     intersector->setEllipsoidModel(em);
 
     _intersectionVisitor.reset();
+    _intersectionVisitor.setTraversalMask(traversalMask);
     _intersectionVisitor.setIntersector( intersector.get() );
     
     scene->accept(_intersectionVisitor);
@@ -1420,12 +1421,12 @@ void ElevationSlice::computeIntersections(osg::Node* scene)
     
 }
 
-ElevationSlice::Vec3dList ElevationSlice::computeElevationSlice(osg::Node* scene, const osg::Vec3d& startPoint, const osg::Vec3d& endPoint)
+ElevationSlice::Vec3dList ElevationSlice::computeElevationSlice(osg::Node* scene, const osg::Vec3d& startPoint, const osg::Vec3d& endPoint, osg::Node::NodeMask traversalMask)
 {
     ElevationSlice es;
     es.setStartPoint(startPoint);
     es.setEndPoint(endPoint);
-    es.computeIntersections(scene);
+    es.computeIntersections(scene, traversalMask);
     return es.getIntersections();
 }
 
diff --git a/src/osgSim/HeightAboveTerrain.cpp b/src/osgSim/HeightAboveTerrain.cpp
index 37ac2e865..967cbbd41 100644
--- a/src/osgSim/HeightAboveTerrain.cpp
+++ b/src/osgSim/HeightAboveTerrain.cpp
@@ -38,7 +38,7 @@ unsigned int HeightAboveTerrain::addPoint(const osg::Vec3d& point)
     return index;
 }
 
-void HeightAboveTerrain::computeIntersections(osg::Node* scene)
+void HeightAboveTerrain::computeIntersections(osg::Node* scene, osg::Node::NodeMask traversalMask)
 {
     osg::CoordinateSystemNode* csn = dynamic_cast<osg::CoordinateSystemNode*>(scene);
     osg::EllipsoidModel* em = csn ? csn->getEllipsoidModel() : 0;
@@ -82,6 +82,7 @@ void HeightAboveTerrain::computeIntersections(osg::Node* scene)
     }
     
     _intersectionVisitor.reset();
+    _intersectionVisitor.setTraversalMask(traversalMask);
     _intersectionVisitor.setIntersector( intersectorGroup.get() );
     
     scene->accept(_intersectionVisitor);
@@ -107,11 +108,11 @@ void HeightAboveTerrain::computeIntersections(osg::Node* scene)
     
 }
 
-double HeightAboveTerrain::computeHeightAboveTerrain(osg::Node* scene, const osg::Vec3d& point)
+double HeightAboveTerrain::computeHeightAboveTerrain(osg::Node* scene, const osg::Vec3d& point, osg::Node::NodeMask traversalMask)
 {
     HeightAboveTerrain hat;
     unsigned int index = hat.addPoint(point);
-    hat.computeIntersections(scene);
+    hat.computeIntersections(scene, traversalMask);
     return hat.getHeightAboveTerrain(index);
 }
 
diff --git a/src/osgSim/LineOfSight.cpp b/src/osgSim/LineOfSight.cpp
index aca733627..62efc4de2 100644
--- a/src/osgSim/LineOfSight.cpp
+++ b/src/osgSim/LineOfSight.cpp
@@ -104,7 +104,7 @@ unsigned int LineOfSight::addLOS(const osg::Vec3d& start, const osg::Vec3d& end)
     return index;
 }
 
-void LineOfSight::computeIntersections(osg::Node* scene)
+void LineOfSight::computeIntersections(osg::Node* scene, osg::Node::NodeMask traversalMask)
 {
     osg::ref_ptr<osgUtil::IntersectorGroup> intersectorGroup = new osgUtil::IntersectorGroup();
 
@@ -117,6 +117,7 @@ void LineOfSight::computeIntersections(osg::Node* scene)
     }
     
     _intersectionVisitor.reset();
+    _intersectionVisitor.setTraversalMask(traversalMask);
     _intersectionVisitor.setIntersector( intersectorGroup.get() );
     
     scene->accept(_intersectionVisitor);
@@ -147,11 +148,11 @@ void LineOfSight::computeIntersections(osg::Node* scene)
     
 }
 
-LineOfSight::Intersections LineOfSight::computeIntersections(osg::Node* scene, const osg::Vec3d& start, const osg::Vec3d& end)
+LineOfSight::Intersections LineOfSight::computeIntersections(osg::Node* scene, const osg::Vec3d& start, const osg::Vec3d& end, osg::Node::NodeMask traversalMask)
 {
     LineOfSight los;
     unsigned int index = los.addLOS(start,end);
-    los.computeIntersections(scene);
+    los.computeIntersections(scene, traversalMask);
     return los.getIntersections(index);
 }