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Computer Aided Geometric Design 29, 2 (2012) 150-161
L-system specification of knot-insertion rules for non-uniform B-spline subdivision
Vincent Nivoliers 1, Cédric Gérot 2, Victor Ostromoukhov 3, Neil F. Stewart 4
(2012-02)

Subdivision schemes are based on a hierarchy of knot grids in parameter space. A univariate grid hierarchy is regular if all knots are equidistant on each level, and irregular otherwise. We use L-systems to design a wide class of systematically described irregular grid hierarchies. Furthermore, we give sufficient conditions on the L-system which guarantee that the subdivision scheme, based on the non-uniform B-spline of degree d defined on the initial knot grid, is uniformly convergent. If n is the number of symbols in the alphabet of the L-system, this subdivision scheme is defined with a finite set of masks (at most nd+1) which does not depend on the subdivision step. We provide an implementation of such schemes which is available as a worksheet for Sage software.
1:  ALICE (INRIA Nancy - Grand Est / LORIA)
INRIA – CNRS : UMR7503 – Université de Lorraine
2:  Grenoble Images Parole Signal Automatique (GIPSA-lab)
CNRS : UMR5216 – Université Joseph Fourier - Grenoble I – Université Pierre-Mendès-France - Grenoble II – Université Stendhal - Grenoble III – Institut Polytechnique de Grenoble - Grenoble Institute of Technology
3:  Département d'Informatique et de Recherche Opérationnelle [Montreal] (DIRO)
Université de Montréal
4:  Laboratoire d'Informatique Graphique de l'Université de Monréal (LIGUM)
Université de Montréal
AGPIG
Computer Science/Computer Graphics and Virtual Reality

Computer Science/Computational Geometry
L-system – Subdivision – Non-uniform