Shape Reconstruction and Recognition with Isolated Non-directional Cues

Abstract: The paper investigates a hypothesis that our visual system groups visual cues based on how they form a surface, or more specifically triangulation derived from the visual cues. To test our hypothesis, we compare shape recognition with three different representations of visual cues: a set of isolated dots delineating the outline of the shape, a set of triangles obtained from Delaunay triangulation of the set of dots, and a subset of Delaunay triangles excluding those outside of the shape. Each participant was assigned to one particular representation type and increased the number of dots (and consequentially triangles) until the underlying shape could be identified. We compare the average number of dots needed for identification among three types of representations. Our hypothesis predicts that the results from the three representations will be similar. However, they show statistically significant differences. The paper also presents triangulation based algorithms for reconstruction and recognition of a shape from a set of isolated dots. Experiments showed that the algorithms were more effective and perceptually agreeable than similar contour based ones. From these experiments, we conclude that triangulation does affect our shape recognition. However, the surface based approach presents a number of computational advantages over the contour based one and should be studied further.