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Proceedings of CAD'16, 2016, 231-236
STEP-compliant Data Exchange of T-spline Models between CAx Systems

Wenlei Xiao, Yazui Liu, Rui Li, Gang Zhao, Beihang University

Abstract. T-spline is a new approach for defining freeform surface with relatively less control points than NURBS and is able to represent a model using a single surface without joining errors. Whereas, the complexity of T-spline data models leads great difficulties to its programming, which hinders the research and development of T-spline technologies. In addition, the data exchange format of T-spline models still remains on a primitive level, and no standards has been published so far. This article gives a reconsideration to the existing T-spline definition, and proposes a set of redesigned data models which have much more understanding conveniences to both human and computer. Moreover, the STEP-compliant data models are designed using the proposed T-spline models, so as to standardize their data exchange between different CAx systems. The combination of T-spline with other product models in ISO 10303 makes it feasible to exchange the versatile resource data in a hybrid neutral file. A prototype system is developed for the validation purpose, which consists of a TSM-to-STEP converter, a STEP parser and a T-spline kernel. Using the developed prototype system, one can automatically convert a TSM file exported from the Rhino system to a STEP file in P21 format, which can be then parsed using the STEP parser and processed in the T-spline kernel. Some testing examples shows that the proposed data models are much more efficient in processing and exchanging the T-spline data.

Keywords. T-spline, Data model, STEP, Data exchange

DOI: 10.14733/cadconfP.2016.231-236