| Popis: |
This paper describes an automatic diagram input system which reads the handwritten piping and instrument diagram and recognizes the symbol, character, and line drawn on the diagram. The object is a handwritten diagram which is easily understandable by the knowledge of the designer under a very mild constraint. The symbols which are the object of recognition are of more than 200 kinds of various sizes. In addition, a large symbol with unspecified shape may be drawn, and there can be various kinds of lines. To cope with such complex diagrams containing a large amount of handwriting distortions, various diagram processing techniques are proposed. Examples are vector representation with a high accuracy, shaping of various distortions, and the two-stage segmentation, where line, symbol and character are separated hierarchically from the vectorized figure. Other examples are the symbol recognition combining a decision tree and pattern matching, and recognition dictionary based on automatic generation of distorted patterns. The developed diagram input system is a flexible system, in which new symbols can be additionally registered, and complex handwritten diagrams can be recognized. A test was made for the system using the actually written design diagrams. The result indicated a practically satisfactory performance, where the processing time is 3 to 8 min for an A3 sized diagram by a large-scale computer and the recognition rate is above 95 percent. |
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