| Determining the 3D layout of a scene is important for things like scene segmentation, path planning, object avoidance, reaching, and grasping. The interaction of light with objects in a scene results in many subtle illumination effects which may be useful cues for spatial layout. Consider for example shadows. Previous research has shown cast shadows to be effective in determining the 3D layout of a scene, and other studies are finding shadows play a role in object recognition. However, even though interreflections are very similar to shadows, little is known about human sensitivity to or the effectiveness of interreflections for similar tasks. I will discuss some of the history and problems concerning investigation of interreflection effects as visual cues, and present some research showing that interreflection is an important cue, both alone and in conjunction with shadows, for establishing spatial layout. |