Finding contour-based abstractions of planar patterns

An algorithm is described to detect a number of points, on the contour of a planar shape, which constitute the vertices of a schematic polygonal representation of the shape itself. A set of points, initially extracted from the chain-coded representation of the contour, is iteratively examined, while removing some points and inserting new ones. The number of selected points decreases in size from iteration to iteration, and the selection process converges towards an expected perceptually significant set of points. The polygon obtained by linking successive points approximates the contour in an intuitive way. It is not constrained within a given tolerance, and is likely to locally change from a coarse to a more faithful approximating shape, in correspondence with contour regions increasing in details.