Research On Content-based Engineering Drawings Retrieval Technology

With the rapid development of the modern technology and sharp expansion of information, it has become the main hard problem of archives department to realize information modernization management, which is how to archive and retrieve the current engineering drawings and document in order to make the drawings and archives effect better. The user not only orients the wanted drawing, but also needs to gather the drawings with the similar structure, what makes it more and more important to do research on the method of engineering drawings retrieval. Combined with the characteristic of engineer drawings, applying image processing technology, this thesis does some deep research on engineer drawings retrieval.Traditional drawings retrieval technology was based on key words while this thesis applies image processing to realize the retrieval of engineering drawings stored in bitmap format. Content-based retrieval method demands that firstly, the scanned engineering drawings are preprocessed, which mainly includes binarization, denoising, edge detection and coordinates regulation, then standardized and saved as XML format, which is prepared for the follow-up feature extraction. Secondly, the engineering drawings features are extracted applying image processing arithmetic. The visual features such as density feature and histogram feature and the imaginative features such as image element tree feature and contour region feature are mainly extracted in this thesis. Finally, the drawings are classified using BP neural network method and on the basis of classification the drawings are retrieved with multi-feature combination method.This thesis presents the implementation of the scheme, designs comparing experiments of four different kinds of drawings, analyses and evaluates on the arithmetic and effect of drawings standardization, image element detection, feature extraction, classification and retrieval etc. We introduce the application in the retrieval of the drawings in the EDM system and get a series of good practical conclusions.