Computer Laboratory

Technical reports

Removing polar rendering artifacts in subdivision surfaces

Ursula H. Augsdörfer, Neil A. Dodgson, Malcolm A. Sabin

June 2007, 7 pages

Abstract

There is a belief that subdivision schemes require the subdominant eigenvalue, λ, to be the same around extraordinary vertices as in the regular regions of the mesh. This belief is owing to the polar rendering artifacts which occur around extraordinary points when λ is significantly larger than in the regular regions. By constraining the tuning of subdivision schemes to solutions which fulfill this condition we may prevent ourselves from finding the optimal limit surface. We show that the perceived problem is purely a rendering artifact and that it does not reflect the quality of the underlying limit surface. Using the bounded curvature Catmull-Clark scheme as an example, we describe three practical methods by which this rendering artifact can be removed, thereby allowing us to tune subdivision schemes using any appropriate values of λ.

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BibTeX record

@TechReport{UCAM-CL-TR-689,
  author =	 {Augsd{\"o}rfer, Ursula H. and Dodgson, Neil A. and Sabin,
          	  Malcolm A.},
  title = 	 {{Removing polar rendering artifacts in subdivision surfaces}},
  year = 	 2007,
  month = 	 jun,
  url = 	 {http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-689.pdf},
  institution =  {University of Cambridge, Computer Laboratory},
  number = 	 {UCAM-CL-TR-689}
}