Hierarchy of surface models and irreducible triangulations

  • Authors:
  • Siu-Wing Cheng;Tamal K. Dey;Sheung-Hung Poon

  • Affiliations:
  • Department of Computer Science, HKUST, Clear Water Bay, Hong Kong;Department of Computer and Information Sciences, Ohio State University, Columbus, OH;Department of Computer Science, HKUST, Clear Water Bay, Hong Kong

  • Venue:
  • Computational Geometry: Theory and Applications
  • Year:
  • 2004

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Abstract

Given a triangulated closed surface, the problem of constructing a hierarchy of surface models of decreasing level of detail has attracted much attention in computer graphics. A hierarchy provides view-dependent refinement and facilitates the computation of parameterization. For a triangulated closed surface of n vertices and genus g, we prove that there is a constant c 0 such that if n c ċ g, a greedy strategy can identify Θ(n) topology-preserving edge contractions that do not interfere with each other. Further, each of them affects only a constant number of triangles. Repeatedly identifying and contracting such edges produces a topology-preserving hierarchy of O(n + g2) size and O(logn + g) depth. Although several implementations exist for constructing hierarchies, our work is the first to show that a greedy algorithm can efficiently compute a hierarchy of provably small size and low depth. When no contractible edge exists, the triangulation is irreducible. Nakamoto and Ota showed that any irreducible triangulation of an orientable 2-manifold has at most max{342g - 72, 4} vertices. Using our proof techniques we obtain a new bound of max{240g, 4}.