@ tjohn: Nice observation, but that works only with primitive objects in Bryce, polygon mesh of the sphere(or cube) will not work, I already tested that (looks that only "render effect" objects, which primitives are, indeed, have volumetric type of refraction, meshes are considered as 2d surfaces in space, as beeing hollow inside). @ Ornly: It is relly not "pushing" things, i believe, were are all just trying to figure out certain aspects of Bryce and it's ray tracing algorithm, cuz it's tottaly undocumented and misterious, looks to me that it's not that simple as some other ray tracing engines... Call me crazy, lol, but i tend to believe that there is a lot of things we do not know happening behind that simple and ellegant interface Bryce have !!! :)