Research On Algorithms Of Repairing STL Files And Transforming IGES Files To STL

The Rapid Prototyping (RP) technology is a new and high technology that combines the CAD, laser, fine mechanics, CNC and new materials. STL is the practically standard document format of Rapid Prototyping System. Because of the limitation of STL, defect of the model which based on STL format is always generated when the STL document is being transmitted from CAD system to RP manufacturing System, which leading the model can not be correctly processed by RP manufacturing system. As a medial document format, IGES is also used widely between different CAD systems. Based on the fruit of previous research, the author has done further research in correcting STL and transforming IGES file to STL files to advance the level of technology of RP system.Firstly, the paper discusses the common errors in the STL models, especially the common misconceptions of STL models which created by the modeling software CATIA. And also it analyzes various methods of correcting (such as Error-Tolerant Slicing, Automatic Error Correction and Manual Correction) and their respective strong points and weaknesses. Combining the strong points both with automatic error correction and manual correction put forward an automatic correction algorithm which based on topological relations in the model and little artificial assistants. This paper introduces the basic ideas and methods of detection and correction of errors in the implementation process. At last, it proves the idea with instances.How to represent CAD system models and the important roles of IGES as a middle file format are discussed. A new arithmetic of transforming IGES files to STL files is presented. Construct entities defined in the file and build the topological connection of entities according to information recorded in entities; spread the three-dimensional surface to planar plane, transform the border loops to the planar plane too, then prune every surface according to the loops in it; triangulate the surface with reserved points in it and points on the loops under the consistency of STL format, and output the legal STL file. The key point of the arithmetic is to ensure the triangles created on the joint of face and face correctly. At last, an instance is introduced.