radiance 4R1+20120125-1build1 (amd64 binary) in ubuntu quantal

 Radiance is intended to aid lighting designers and architects by
 predicting the light levels and appearance of a space prior to
 construction. The package includes programs for modeling and translating
 scene geometry, luminaire data and material properties, all of which are
 needed as input to the simulation. The lighting simulation itself uses
 ray tracing techniques to compute radiance values (ie. the quantity of
 light passing through a specific point in a specific direction), which
 are typically arranged to form a photographic quality image. The
 resulting image may be analyzed, displayed and manipulated within the
 package, and converted to other popular image file formats for export to
 other packages, facilitating the production of hard copy output.