In 1968 Guzman showed how the myriad of surfaces composing a highly complex and novel assemblage of volumes can be readily assigned to their appropriate volumes in terms of the constraints offered by the vertices of coterminating edges. Of particular importance was the L-vertex, produced by the cotermination of two contours, which provides strong evidence for the termination of a 2D surface. An X-junction, formed by the crossing of two contours without a change of direction at the crossing, played no role in the segmentation of the scene. If the potency of noise elements to affect recognition performance reflected their relevancy to the segmentation of scenes, as suggested by Guzman, X-junctions would be expected to have little or no effect on shape-based object recognition whereas L-junctions would be expected to have a strong deleterious effect when disrupting the smooth continuation of contours. Guzman’s roles for the various vertices and junctions have never been put to systematic test with respect to human object recognition. By adding identical noise contours to line drawings of objects that produced either L-vertices or X-junctions, these shape features could be compared with respect to their disruption of object recognition. Guzman’s insights that irrelevant L-vertices should be disruptive and irrelevant X-vertices would have minimal effect were confirmed.
Survey on Shape Description and Recognition Techniques
