That's a very instructive example. Thanks, Jeff01! Incidentally, does anyone know how refraction is computed in Firefly? I mean, is it physically correct in the sense that both the front and back face change the direction of the light? If so, what if an object only had a front face? I just had that crazy thought that maybe the transparent white sphere might be taken as an object with a different refractive index. I don't think, however, that the problem with transparent objects is necessarily related to the bump map problem. I will try the scaling approach richardson proposed to see if it solves that issue and post my findings here.

-- I'm not mad at you, just Westphalian.