A predictive Kalman-Bucy-Filter controls the matched scanning of an optical contour sensor to track contours and extract contour parameters. Contours are disassambled into segments with a steady parameter set. Parameter data are composed into a relational graph structure for syntactic pattern recognition in the field of robot vision. Immediate applications of contour tracking include analysis of threadlike molecules and aerodynamic flow patterns, control of edge welding and visual inspection. Matched scanning and Kalman Filtering cope with weak and broken contours in highly structured backgrounds. Selection of pictorial data reduces computer workload to the real time capacity of a PDP 11/23 minicomputer.