Scaling of an external TransformGroup


to display a wire frame of my original data i pass a BranchGroup to the DisplayRenderer by

DisplayRendererJ3D dr = DisplayRendererJ3D)display3D.getDisplayRenderer();
 TransformGroup displayTG = dr.getTrans ();

Now the problem is the scaling of the wire frame (I use the same data as for the constructing of the Irregular3DSet.) On the display the wire frame has a dimension that is about 10 times of the visad data.
instead of getting the TransformGroup i also tryed it with

BranchGroup bgRoot = dr.getRoot();

The result is the same.
Has anyone an idea what is going wrong?