Stephen T. Barnard

IJCAI Conference 1987 Conference Paper

Stereo Matching by Hierarchical, Microcanonical Annealing

• Stephen T. Barnard

AAAI Conference 1986 Conference Paper

A Stochastic Approach to Stereo Vision

• Stephen T. Barnard

A stochastic optimization approach to stereo matching is presented. Unlike conventional correlation matching and feature matching, the approach provides a dense array of disparities, eliminating the need for interpolation. First, the stereo matching problem is defined in terms of finding a disparity map that satisfies two competing constraints: (1) matched points should have similar image intensity, and (2) the disparity map should be smooth. These constraints are expressed in an ‘ (energy” function that can be evaluated locally. A simulated annealing algorithm is used to find a disparity map that has very low energy (i. e. , in which both constraints have simultaneously been approximately satisfied). Annealing allows the large-scale structure of the disparity map to emerge at higher temperatures, and avoids the problem of converging too quickly on a local minimum. Results are shown for a sparse random-dot stereogram, a vertical aerial stereogram (shown in comparison to ground truth), and an oblique ground-level scene with occlusion boundaries.

AIJ Journal 1983 Journal Article

Interpreting perspective images

• Stephen T. Barnard

A fundamental problem in computer vision is how to determine the 3-D spatial orientation of curves and surfaces appearing in an image. The problem is generally underconstrained, and is complicated by the fact that metric properties, such as orientation and length, are not invariant under projection. Under perspective projection (the correct model for most real images) the transform is nonlinear, and therefore hard to invert. Two constructive methods are presented. The first finds the orientation of parallel lines and planes by locating vanishing points and vanishing lines. The second determines the orientation of planes by ‘backprojection’ of two intrinsic properties of contours: angle magnitude and curvature.

AAAI Conference 1980 Conference Paper

Automated Inspection Using Gray-Scale Statistics

• Stephen T. Barnard