Sketch-Based Engineering Drawing Retrieval Technology Research And Application

The project engineers spend much time in looking up drawings which they need, therefore how to speedily, accurately search out the required drawings from the database is especially important to them. The existing Drawing File Management System generally searches the drawing file based on the keywords such as project, person and date. The merit of this keywords retrieval way is that the retrieval speed is very quick, the technology is simple and the search is convenient. However, this retrieval way has lots of limitations such as manual label is time-consuming and laborious, keywords can not reflect the actual contents of drawing file, and the engineering drawing is very difficult to be described through keywords.In allusion to deficiency which exists in searching manner based on keywords, this paper introduces the sketching technology to the retrieval of drawing file. First, the paper presents a sketch-based engineering drawings retrieval framework basing on the analysis and summing-up of the related technology which is composed of retrieval condition preprocessing, feature extraction, shape matching and relevance feedback. Second, it brings a XML-based engineering drawings storage model and introduces information representations, transmission proceeding of the model detailedly; meanwhile it gives the XML representation of the engineering drawings which includes composing information of the drawings and the primary feature information which makes the retrieval simple. Third, it accomplishes denoising and simplifying of the input condition, recognizes the sketch into three primitive shapes. And then it takes 8 kind spatial relation of the primitive shape as matching feature, brings a graphic matching method based on spatial relation, emphasis placed on introducing spatial feature extraction, feature dimension reduction, theory of similarity computing and implementing method. At last, it completes the design and development of the sketch-based engineering drawings retrieval system in a preliminary application of practical projects.