Analysis of three-dimensional splines and their application to the initial graphics exchange specification
This research develops the fundamental theories associated with three-dimensional splines and the philosophies underlying the Initial Graphics Exchange Specification (IGES). Splines have been classified into three main categories: polynomial splines, splines-in-tension, and blending splines. The importance of a three-dimensional spline standard is given. It is shown that no single spline routine can adequately define a curve for every possible application. A possible three-dimensional spline standard should therefore contain a spline routine from each of the three categories. The B-spline, Cline's spline-in-tension, and Circle Spline were the three spline routines selected. The properties and characteristics that these splines should possess are defined. Two methods for extending a two-dimensional spline into three dimensions are given. The B-spline is extended parametrically and the Spline-in-Tension is extended explicitly. It will be shown that the parametric form is the more powerful and computationally efficient method. An alternative method for representing splines in IGES is presented. This alternate method uses the IGES Copious Data Entity. It has a smaller file size than the traditionally used Parametric Spline Curve Entity. The use of this method is geared toward the application of splines in design and analysis work. The data stored within the file by each spline routine represents the minimum amount of information required to uniquely define the spline curve. The alternative method for storing and transferring spline data is structured in a manner that allows each spline routine to read and write files efficiently. Using this data file, a spline routine can generate a curve by reading the output of another spline routine. It will be demonstrated that spline transfer between both similar and dissimilar spline routines can be done accurately and efficiently. 72 refs., 16 figs.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5200025
- Report Number(s):
- LA-10509-T; ON: DE86001241
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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