I've been using the method described in the "Tips and Tricks" at triaxialdesign.com (spherical environment, constant illumination, etc.) For some materials, like galvanized, it seems fine, but for others, it has choppiness, as the part will go from one shade of gray to another without blending together. I've tried messing with all of the settings, but I can't figure out why it behaves this way. If I use a more standard way of lighting, it seems fine. Any suggestions?