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A Parser that Converts a Boundary Representation into a Features Representation



Thomas R. Kramer


The VWS2 B-rep Parser is a computer program written in LISP that takes a file giving the boundary representation of a part as input and produces a file giving a feature-based representation of the part as output. The format of the input file is a PDES/STEP boundary representation, and the format of the output file is that required by the VWS2 system of the NIST AMRF. The parser deals with a limited range of two-and-a-half dimensional parts. The general approach to parsing is to expect that the part is parable and look for arrangements of faces which are the signatures of features. The initial implementation of the approach recognizes five feature types. The approach is extendible to a wider range of feature and subfeature types, and to parts which have features made from several sides. Parts having features which intersect in a complex manner are likely to test the limits of this approach, or be beyond the limits. With the addition of this parser, the AMRF Vertical Workstation is capable of making a part from a PDES/STEP file without human intervention.
NIST Interagency/Internal Report (NISTIR) - 3864
Report Number


boundary representation, LISP, parser, PDES, STEP, VWS2


Kramer, T. (1988), A Parser that Converts a Boundary Representation into a Features Representation, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 19, 2024)


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Created January 1, 1988, Updated October 16, 2008