Development Of The Intelligent Sketch System Based On Engineering Drawing

With the development of CAD technology, three-dimensional CAD software whosefunctions become more powerful and perfect has been one of the most importantengineering software to design productin the field of engineering design. During theprocess of transition from2D design to3D design, a large number of engineeringdrawings produced because of2D design in the previous need to be converted into3Dmodeling, so that they become the basis of3D design about therevised products.Therefore, compared to the problem of the low efficiency of manual modeling, anefficient3D modeling method based on engineering drawing becomes focused on bythe enterprises.Because3D reconstruction technology based on the engineeringdrawing is still not applied in practice, an intelligent sketch system based engineeringdrawing is developed on the VC++6.0platform in this paper, which can convert theengineering drawing to the sketch characteristic in3D CAD software.Three techniques about system development are studied in the paper, includingUG/Open technology, database technology and3D reconstruction pre-processingtechnology.In the paper, the principle of UG/Open and theprocess of the systemdevelopment are introduced. And the database of system is established to managethedata exchange among the various modules ofsystem.The3D reconstructionpretreatment technology as the core of the system composition becomes the keyresearch object, and some improvement is put forward.Firstly, the structure of DXF fileis studied to read the information about the entities section and layer. Secondly, thepretreatment of the data as input in the system is researched. Combining the improvedcoordinate projection and the improved turn-to-leftmost proposed,a selected viewsegmentation algorithm is come up with, which can segment the view thoroughly andhas high efficiency. Finally, some problems in the view-folding section are studied,such as view adjacency, view origin, view coordinate system transformation and viewplacental face coordinate matrix. The coordinate transformation matrix and placentalface matrix of the view which is adjacent to one of three view types including frontview, top view and left view in the same coordinate system are proposed.In the paper, the feasibility of the system is verified by using a large number ofengineering drawings and the system turns the engineering drawing into sketch featurein UG modeling. Therefore, the system makes up for the deficiency of the existing software function, solves the problem of fast3D modeling based on the engineeringdrawing, and lays the foundation for the further research on3D reconstruction basedon engineering drawing.