Constrained scaling of trimmed NURBS surfaces based on fix-and-stretch approach

Citation
C. Zhang et al., Constrained scaling of trimmed NURBS surfaces based on fix-and-stretch approach, COMPUT AID, 33(1), 2001, pp. 103-112
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Computer Science & Engineering
Journal title
COMPUTER-AIDED DESIGN
ISSN journal
0010-4485 → ACNP
Volume
33
Issue
1
Year of publication
2001
Pages
103 - 112
Database
ISI
SICI code
0010-4485(200101)33:1<103:CSOTNS>2.0.ZU;2-D
Abstract
A new method to scale a trimmed NURBS surface while holding the shape and s ize of specific features (trimming curves) unchanged is presented. The new method is fix-and-stretch based: the new surface is formed by fixing select ed regions of the given trimmed NURBS surface that contain the trimming cur ves and stretching the remaining part of the surface to reach certain bound ary conditions. The stretching process is performed using an optimization p rocess to ensure that the resulting surface reflects the shape and curvatur e distribution of the scaled version of the given surface. The resulting su rface maintains a NURBS representation and, hence, is compatible with most of the current data-exchange standards. The new approach is more robust tha n a previous, attach-and-deform based approach (Zhang P, Zhang C, Cheng F. Constrained shape scaling of trimmed NURBS surfaces. In: Proceedings of the 1999 ASME Design Theory and Methodology Conference. Las Vegas, Nevada, 199 9) in that it can tolerate scaling factors of bigger values (up to 2 in som e cases). The new approach also guarantees that the features remain exactly the same after scaling. Test results on several car parts with trimming cu rves and comparison with the previous approach are included. The quality of the resulting surfaces is examined using the highlight line model. The pre sented technique is important for integrating standard parts into a sculptu red product. (C) 2000 Elsevier Science Ltd. All rights reserved.