Recognition System Research Of Engineering Diagram Drawing Based On Cross Point Extraction

The recognition of scanned image of documents drawing is an important study object in fields of CAD/CAM and pattern recognition, such as engineering drawing and form drawing recognition. However, few work had been done in the past about scanned image of engineering diagram .The first chapter of this paper mainly reviews the existing research, describes the advantage and weak points of each method, and at the same time builds our own general theory framework in order to guide the research of engineering diagram recognition. According to the structure and characteristic of diagram, the pre-processing technology of diagram image, the vectorization of coordinate lines and curves in the diagram, the recognition of coordinate scale number, and user query function are discussed in detail in the remaining parts of the paper.The second chapter gives the system design of diagram image recognition, selects a suitable developing environment by analyzing the function and capability requirement of diagram image recognition system. The whole system is divided into diagram recognition module and user query module on the basis of module division principle and fact-requirement.The third chapter describes the preprocessing technology of diagram image recognition. A noise filtering method based on mathematical morphology is introduced. Based on HOUGH transform, the methods of diagram adjust and image-character separation is also proposed in the chapter.The forth chapter discusses the kernel algorithm of diagram image recognition. The analysis of the recognition algorithm of engineering drawings and form drawings has showed that the distortion near cross point area is always a hard problem in drawing vectorization. So different methods are given to deal with different objects such as coordinate lines and curves in diagram iamge. To get information of coordinate lines, a vectorization method based on cross point extraction is presented creatively, and for the curve objects in the image, another adaptive tracking processing method based on slope is presented.The fifth chapter deals with the printed digit process in diagram image. A pattern match method based on digit mass center is introduced to achieve the recognition of scale digits in diagram image.The sixth chapter introduces the design of pre-modules and pro-modules in diagram image recognition system. Based on technology of image process, computergraphic, and database, the design of sub-modules is discussed in detail.