Study Of STEP-based System Of The File Character Recognition

The STEP(Standard for the Exchange of Product Modal Data)which is issued by the International Organization for Standardization is an international standard of the data exchange of the industry production. The standard is to study the technology of the data exchange of the production model. Basing on the STEP, the data of the production can be described and exchanged completely in the full lifecycle and this makes all the application systems receive and share all the data information without manpower. Because of the widely acceptance of the standard–based production data management, the STEP is well known as one of the most important methods that can make the corporation more competitive and as a more perfect standard of the production data exchange, STEP is used more widely.The NURBS (Non-Uniform Rational B-Spline) is the most practical curve theory in the description of the curve and the surface. Because of the prominent advantage, NURBS is the only way of mathematical description to define the geometry of the industry production in STEP.The dissertation is on the development of the STEP-based file recognition system. As a part of the CAD files recognition system in the CMM (Coordinate Measuring Machine), the system provides graphics file interface for the intelligent CMM. Basing on the description of the entity information in the STEP, this system extracts the data information of the 3-dimensional models of the production from the STEP neutral files and then processes the data using NURBS. The main content of the dissertation is as follows:1. Summarizing the development of the CMM technology, and the aims, significance, and the methods of the dissertation are presented too.2. Summarizing the development and the main content of the STEP, detailed analysis and study of the methods, structure and formats of the neuter exchange files of the STEP are presented.3. The methods of the graphics description in the STEP are studied, and the Boundary Representation in the neuter files, especially the description of the geometry and the topology information are analyzed in the dissertation.4. The dissertation gives a specific design of the STEP character extracting system including the entity information extracting module, the entity information processing module and the entity displaying module.5. Designing of test method, and analyzing the results after the test.6. The conclusion of the research and the future study are given.