3D Reconstruction From Engineering Drawings: Theory And Algorithm Realization

As an effective expression way of product design, engineering drawings are widely used and play an important role in traditional industry. It's easy for trained engineer to understand the solid model and product design expressed in the drawings. Because of the wide use of 3d CAD/CAM software, product design needs to be put in 3d space but there are large numbers of drawings that haven't been converted to 3d model. The manual converting needs much manpower and its time costs are also considerable. So the research on automatic 3d reconstruction from engineering drawings is very necessary. However, in the past research work, drawing rules and common features of usual parts are not investigated deeply, and also the computation complexity of existing 3d reconstruction algorithms is rather high. Therefore based on the summary on its research backgrounds and realization of the pretreatment technology of 3d reconstruction from engineering drawings, semantic information and contour information in engineering drawings are analyzed carefully and the reconstruction algorithms using such information are proposed. Moreover the problem of parameterization of 3d model acquired in reconstruction is particularly discussed. Firstly the past 3d reconstruction algorithms are overviewed and classified, among which existing multi-view 3d reconstruction approaches are discussed in detail. Then the pretreatment technology of 3d reconstruction from engineering drawings, by which the original data of engineering drawings is converted to the format that can be used by reconstruction algorithms, is discussed and realized. For concreteness, the data structure for 3d reconstruction is proposed; the drawing dividing and coordinate system converting algorithm, implied points processing algorithm, and view contour recognizing algorithm are researched and realized. Thereby based on analyzing the semantic information in engineering drawings, engineering semantics is used to guide the 3d primitive identification process, and with that the 3d reconstruction algorithm using engineering semantics is proposed and its affectivity is demonstrated by one application. Further, boundary information of orthographic views is analyzed in detail and then 3d reconstruction algorithm using 2-stage extrusion is presented. At last features of 2d views are discussed to establish 3d parameterization feature model in 3d reconstruction process, which indicates that the solid model acquired by 3d reconstruction can be used directly in parametric design.