diff --git a/common/BaseObjectData.cc b/common/BaseObjectData.cc
index 2bba4b40c34903b997585d03f8ee89a89f8c58eb..38e8f87626b34a40158fffd16e9b60c9506d2728 100644
--- a/common/BaseObjectData.cc
+++ b/common/BaseObjectData.cc
@@ -270,6 +270,10 @@ MaterialNode* BaseObjectData::materialNode() {
   return materialNode_;
 }
 
+const MaterialNode* BaseObjectData::materialNode() const {
+    return materialNode_;
+}
+
 BoundingBoxNode* BaseObjectData::boundingBoxNode() {
   return boundingBoxNode_;
 }
diff --git a/common/BaseObjectData.hh b/common/BaseObjectData.hh
index 61807d044080ab2ddac066eea16e827dd21137f1..82abfba5f2f0c40faf3f5099e3c78d736a1bc986 100644
--- a/common/BaseObjectData.hh
+++ b/common/BaseObjectData.hh
@@ -193,7 +193,10 @@ class DLLEXPORT BaseObjectData : public BaseObject
 
     /// get a pointer to the materialnode
     MaterialNode* materialNode();
-
+    
+    /// get a const pointer to the materialnode
+    const MaterialNode* materialNode() const;
+    
     /// get a pointer to the bounding box node
     BoundingBoxNode* boundingBoxNode();