From BZFlag Developers:
BRL-CAD is a constructive solid geometry solid modeling system with over 20 years development and producation use by the U.S. military. BRL-CAD includes an interactive geometry editor, parallel ray tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, image and signal-processing tools.
What's new in this version:
Version 7.22 has updated several geometry converters.