Online hand-sketched figure recognition

Abstract An online algorithm capable of recognizing hand-sketched symbols such as those used in flowcharts is presented. The algorithm requires no indication of symbol segmentations and no restrictions on the stroke sequence of symbols. The algorithm has three steps: (1) candidate figure extraction for each symbol based on a graph search and distance calculation between candidate figures and reference patterns, (2) selection of the symbol sequence which minimizes the total sum of these distances, (3) connection rules application. A recognition test performed on 100 hand-sketched flowcharts and block diagrams produced a recognition rate of 96.1%.