Original Date: 05/08/1995
Revision Date: 01/18/2007
Best Practice : Parametric Evaluation of Loft and Other Surface Data
McDonnell Douglas Aerospace (MDA)-St. Louis uses a parametric evaluator to facilitate the exchange of loft and other surface definition data with incompatible CAD systems. This evaluation results in no loss of definition or accuracy of the original data. This standardization method represents all curves by one generic mathematical view, and all surfaces are also represented by one mathematical view. Parametric evaluation is the application of these mathematical procedures to precisely present the real space representation from the parametric representation.
Exchanging geometric (or loft) data between differing automated applications requires a data conversion to accommodate different algorithms used by different vendors and applications. Because this conversion introduces difficulties such as discontinuities, overlaps, intersections, and data expansion, MDA-St. Louis creates or requests executable modules that enable it to use the loft data from 80 different applications without having to convert it. Some of these executable programs are proprietary; MDA-St. Louis consequently does not have access to the code. The original native data is used, but the algorithms are translated by the modules into the standard generic mathematical formula for curves and a standard generic mathematical formula for surfaces. This enables MDA-St. Louis to access loft data from a variety of applications and CAD systems and use the data without a continuous evaluation of each use since the approach has been fully validated for each executable module and application.
For more information see the
Point of Contact for this survey.