Pixie is a free, open source, photo-realistic ray-tracing renderer for generating photo-realistic images. Developed by Okan Arikan and George Harker from the University of Texas, Austin.
Pixie is a RenderMan-like photo realistic renderer. It has been developed as a useful graphics research tool and for people who can not afford a commercial renderer. Pixie is licensed under GNU Public License. Most important features are: Reyes style rendering, motion blur, depth of field and global illumination.
Pixie is popular with students learning the RenderMan Interface, and a suitable replacement for it. It compiles for Windows, Mac, Linux and Unix.