References: 
  Cohen and Wallace, Radiosity and Realistic Image Synthesis
  Sillion and Puech, Radiosity and Global Illumination
  Thanks to Leonard McMillan for the slides
  Thanks to François Sillion for images

A powerful demonstration introduced by Goral et al. of the differences between radiosity and traditional ray tracing is provided by a sculpture by John Ferren. The sculpture consists of a series of vertical boards painted white on the faces visible to the viewer. The back faces of the boards are painted bright colors. The sculpture is illuminated by light entering a window behind the sculpture, so light reaching the viewer first reflects off the colored surfaces, then off the white surfaces before entering the eye. As a result, the colors from the back boards “bleed” onto the white surfaces.