Edge tracing in a priori known direction

This paper presents a contour tracing algorithm based on a priori knowledge about searched edges. The algorithm is destined to trace edges having long fragments of approximately constant direction. This enables the implementation of one edge detector mask only in a given area and simplifies the thinning procedure. The way of searching for starting points is discussed as well as choosing and joining fragments of edges assuring the best correspondence between the found edge and the knowledge possessed. The algorithm shows good insensitivity to noise and local edge distortions.