Accession Number : ADA114789

Title :   The Implicit Constraints of the Primal Sketch.

Descriptive Note : Memorandum rept.,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE ARTIFICIAL INTELLIGENCE LAB

Personal Author(s) : Grimson,W E L

PDF Url : ADA114789

Report Date : Oct 1981

Pagination or Media Count : 37

Abstract : Computational theories of structure-from-motion and stereo vision only specify the computation of three-dimensional surface information at points in the image at which the irradiance changes. Yet, the visual perception is clearly of complete surfaces, and this perception is consistent for different observers. Since mathematically the class of surfaces which could pass through the known boundary points provided by the stereo system is infinite and contains widely varying surfaces, the visual system must incorporate some additional constraints besides the known points in order to compute the complete surface. Using the image irradiance equation, we derive the surface consistency constraint, informally referred to as no news is good news. The constraint implies that the surface must agree with the information from stereo or motion correspondence. and not vary radically between these points. An explicit form of this surface consistency constraint is derived, by relating the probability of a zero-crossing in a region of the image to the variation in the local surface orientation of the surface, provided that the surface albedo and the illumination are roughly constant.

Descriptors :   *Visual perception, *Space perception, *Mathematical analysis, Surfaces, Shape, Images, Radiance, Orientation(Direction), Regions, Equations, Consistency, Algorithms, Interpolation, Albedo, Artificial intelligence

Subject Categories : Psychology
      Anatomy and Physiology
      Theoretical Mathematics

Distribution Statement : APPROVED FOR PUBLIC RELEASE