Engineering drawing recognition based on a line decomposition and re-composition method

A novel drawing recognition system that works efficiently is presented. The authors introduce a novel representation of input images for drawings with breaks and touching lines. The representation involves both geometric and topological information described in terms of line segments. This representation permits drawing recognition through the processes of primitive decomposition and object extraction. The primitive decomposition process splits every black region in an image into primitive line segments, and generates an intermediate description. Next, the object extraction process groups the primitive lines into such meaningful sets as character strings, symbols, and lines by recognition techniques based on the intermediate description. The proposed technique has been applied to a recognition system for complicated drawings such as equipment diagrams superimposed on a map, and to a system which can extract lines from mechanical drawings