[vtkusers] depthbuffer issue?

[Flanery Jr, Raymond E.]

I have a set of bldg footprints for nashville that I have cut down to about 850 bldgs. I am trying to extruding  them in vtk and am having the problem that as I move around in the data set triangles are being constantly drawn improperly, almost like the normals are flopping around. If I extract a smaller set of the buildings, say 5-20 everything looks normal, same code. Any suggestions for what I am seeing?

Ray Flanery