Approximate Spatial Layout Processing in Early Vision

atial orientations of major elements in the visual input, thereby obtaining a rough sketch of the spatial layout. We are investigating the mechanisms by which the visual system can extract this from monocular views of natural scenes. Texture is one well-known source of information that the visual system can exploit (Gibson, 1950). Patterns of texture can be obtained even from brief glimpses, during which a scene will appear static and motion cues are unavailable, and at distances and visual angles at which the effectiveness of stereopsis is limited. Visible texture and texture gradients, arising from markings on surfaces or the spatial arrangements of objects, are useful sources of information both for segregating different regions in a scene and for estimating spatial properties such as surface orientation (Watt, 1995). Texture and texture gradients can be characterized in terms of the local spatial-frequency content at different points in an image (Bajcsy & Lieberman, 1976). It is w