Number of Solutions for Motion and Structure from Multiple FrameCorrespondence

  • Authors:
  • Robert J. Holt;Arun N. Netravali

  • Affiliations:
  • Bell Laboratories, Murray Hill, New Jersey 07974/ E-mail: rjh@research.bell-labs.com, ann@research.bell-labs.com;Bell Laboratories, Murray Hill, New Jersey 07974/ E-mail: rjh@research.bell-labs.com, ann@research.bell-labs.com

  • Venue:
  • International Journal of Computer Vision
  • Year:
  • 1997

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Abstract

Much of the dynamic computer vision literature deals with thedetermination of motion and structure by observing two frames captured at twoinstants of time. Motion prediction and understanding can be improvedsignificantly, particularly in the presence of noise, by analyzing an imagesequence containing more than two frames. In this paper, we assume knowledgeof correspondence of points on the surface of an object which is moving withconstant motion, i.e., constant translation and constant rotation around anunknown center. We give a new formulation of the problem and prove that thefollowing results hold in general for the number of solutions to motion andstructure values (i.e., values of translation, rotation, and depth): (a) For three point correspondences over three views, there are at mosttwo solutions, only one of which has all positive depth values; (b) For two point correspondences over four views, there is a uniquesolution; (c) For one point correspondence over five views, there can be up to tensolutions; (d) For one point correspondence over six views, there is a uniquesolution. The method of solution for each of the above formulations requires thesolving of a system of multivariate polynomials, whose coefficients arefunctions of the observed data. In order to determine the number of solutionsto these systems, we use theorems from algebraic geometry which imply thatunder a few mild conditions, the number of solutions at one set of datapoints provides an upper bound on the number of solutions for almost all setsof data points.Thus a bound on the number of solutions is obtained when asingle system is solved by a method such as homotopy continuation, which weuse here.