POV-Ray (Persistence of Vision Raytracer) is a free raytracing program available on Windows, Mac OS x and Linux

POV-Ray has been around for over a decade now and is full of features. It allows you to render 3d scenes with photo realistic results. Check out the Pov-Ray website for examples of work created with POV-Ray.

Ray tracing is a term used to simulate light bouncing around a 3D envirionment, With POV-Ray you can set up a camera, a light source, add objects and textures. Textures can also effect the way light bouces. For example a metalic texture would create reflections whereas a cloth texture would more likely absorb light. POV-Ray takes all this into account.

To be able to create good looking images does require a steep leraning curve but the results are well worth it. Scenes are created using it's own sort of scripting language. But there are many tools available for use with POV-Ray, like animation programs and mesh editing tools. These can be found on the POV-Ray website.