LuxRender is a physically based and unbiased rendering engine.  Based on
state of the art algorithms, LuxRender simulates the flow of light according
to physical equations, thus producing realistic images of photographic
quality.  Some of the main features of LuxRender are:

  * biased and unbiased rendering: Users can choose between physical
    accuracy (unbiased) and speed (biased);
  * full spectral rendering: Instead of the RGB colour spectrum, full
    spectra are used for internal calculations;
  * hierarchical procedural and image based texture system: Procedural and
    image based textures can be mixed in various ways, making it possible to
    create complex materials;
  * displacement mapping and subdivision: Based on procedural or image
    textures, object surfaces can be transformed;
  * network and co-operative rendering: Rendering time can be reduced by
    combining the processing power of multiple computers;
  * perspective (including shift lens), orthographic, and environment
    cameras;
  * HDR output: Render output can be saved in various file formats,
    including .png, .tga, and .exr.

Fully functional exporters are available for Blender and Maya, while
exporters for a growing number of 3D applications are under development.

WWW: http://www.luxrender.net/