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Based on the detailed analysis of the STL file format, VC++ 6.0 programming language was used to extract the STL ASCII and binary file information, at the same time, using the OpenGL triangle drawing technology for graphical representation of the STL file, with rendering functions such as material, coordinate transformation, lighting, et al, finally realizing the loading and three-dimensional display of STL ASCII and binary file formats.

In the paper, a new method called Boundary Search Method (BSM) for generate regular grids was studied, and the key techniques of BSM were investigated, they are: 1) when searching boundary grids of the solid model described by STL file, to avoid losing grids, a method named Triangle Contraction Searching Method (TCSM) was put forward to get points coordinate to calculate grids No. 2）to get more accurate boundary mesh, a vector method was given to judge and eliminate invalid grids. 3) After identifying all boundary grids, for getting inner grids of the shape, an algorithm called Outer Seed Grid Method (OSGM) was put forward. Finally, two examples were given to show the validity of our principle.

Aiming at the disadvantage of slicing STL model in rapid prototyping, a method of slicing CAD model directly is proposed to advoid the precision damage during converting CAD model to STL file. The effect of the staircase error to the part surface is analyzed, and an algorithm of compensating the section contour is proposed to eliminate the layers’ volumetric difference and improve the part surface precision. The test shows that the methods can obtain the accurate sections of CAD model and improve the part’s shape and size precision.