Forgot to cc the list. So to summarize: There some major bugs fixed with the X3D ribbon output in chimera version 1.2180 that affected the Renderman and POV-ray output as well. So please upgrade your chimera. I think I have fixed all of the problems, so if it still fails, please submit a bug report (ideally with enough data to reproduce the problem). As for vrml output, the xslt technology is slow, but works. In the X3dToVrml97.xslt file, it suggests using saxon.sourceforge.net's java-based converter, and I second that recommendation (it was the fastest of the alternatives I tested). Even when the X3dToVrml97.xslt method works, it has problems -- it outputs VRML 3.0 and most VRML importers expect VRML97 aka VRML 2.0. This is especially problematic for ribbons because ribbons use triangle strips for their geometry and 3.0 supports triangle strips while 2.0 doesn't. VRML97 doesn't support translucent colors either. Consequently, I have put improving the VRML output on my list of things to do. And if you have the option of using the Renderman output, use it, because it reproduces what you see in the chimera window the best of the various export formats. Greg Couch UCSF Computer Graphics Lab