Well, POVRay 3.0 has just fairly recently been released for Linux... It's
got more features than most any other free/shareware raytracer you'll
find. True, the interface isn't point and click, but it really doesn't
have to be. What i would do is basically go through the documentation,
and get some of the basic command line options down. Make yourself a few
scripts with descriptive names (like quick, med, and allnighter) to use to
launch povray with appropriate command line options.
Unfortunately, i haven't really looked very hard for a good modeller for
linux, so i don't have much input for you there. There are alot of
scientific/research type programs out there that could be used for
physical modelling (molecules, inertial stuff (look for 'aero')), and
fractint for some beautiful fractal heightfields. Even if you can find a
good modeller for your mac, POV is POV, and it will render on linux after
being modelled on the Mac.
There is a nice interface for povray for controlling all the options:
http://www.veryComputer.com/~mallozzir/
Additionally there is sceda, a scene animator (I am not so convinced about
that, because the interface is not so self explanatory...)
and ac3d which looked very nice, but is shareware.
The images for the program at the below www-address are raytraced with
povray-2.2 under linux.
Okidoki,
Stefan.
+---------+
|Gib GATES| MS-Windows: The only computer virus
|k e i n e| with a user interface.
|Chance !!|
+---------+
Check out for http://www.veryComputer.com/~sauron/*sp/matrix.htm