The Intelligent Understanding And 3D Reconstruction Based On 2D Engineering Drawing

The Intelligent Understanding and 3D reconstruction based on 2D engineering drawing is a typical intersecting project of computer vision, computer graphics and computer-aided design. It is a reconstruction procedure of 3D solid through identifying and processing the geometric and topologic information of 2D drawing by computer.2D drawing implies the engineering criterions and accustomed engagements of certain fields, besides showing the geometrical projection relationships, so the Intelligent Understanding and 3D reconstruction is a hard research project of artificial intelligence. The main work of this thesis is summarized as follows: firstly, expression information and the semantics of 2D drawing are analyzed; secondly, the structure of DXF file and the extraction methods of graphic primitives are introduced; lastly, a prototype of 3D reconstruction system is developed based on SolidWorks2003 platform with the main stages of view detach, outline search and solid reconstruction.The thesis emphasizes on improving an algorithm of outline search. The key point of outline search is how to select the next path when two or more paths are met at the branch. The algorithm utilizes the rotating transformation theory of vector, and derives a mathematical expression of trigonometric function which has the interval monotonicity. By comparing the values of mathematical expressions, the sizes of the angles can be judged, this avoids the troublesome calculations of angles, diminishes errors and raises efficiency.The prototype of 3D reconstruction system uses the DXF file as the data source. In the pre-treatment stage, the information of graphic primitives is stored into the corresponding data structures, and the outlines of each view are searched automatically. Then the views are transformed into the 3D coordinate system, and the 3D solid can be reconstructed by extruding and cutting operations. Finally, post-treatment is performed to complete the reconstruction procedure with the aid of human-machine interaction. Experimental results show the prototype system can satisfy the reconstruction needs of general solids of revolution and extrusion.