Looks from the section on pre-production in the Wikipedia article like the CGI was handled by four different companies, although MAGI did the majority of it. All of the companies likely used in-house software, as that was a very new field at the time, and it seems that none of them released any commercial rendering software later, although some of the people involved went on to found Wavefront.
One of the computers was the
Super Foonly, the fastest PDP-10 ever built.
