Consistent Digital Rays

  • Authors:
  • Jinhee Chun;Matias Korman;Martin Nöllenburg;Takeshi Tokuyama

  • Affiliations:
  • Tohoku University, Graduate School of Information Sciences, Sendai, Japan;Tohoku University, Graduate School of Information Sciences, Sendai, Japan;Karlsruhe University and Karlsruhe Institute of Technology (KIT), Faculty of Informatics, Karlsruhe, Germany;Tohoku University, Graduate School of Information Sciences, Sendai, Japan

  • Venue:
  • Discrete & Computational Geometry - Special Issue: 24th Annual Symposium on Computational Geometry
  • Year:
  • 2009

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Abstract

Given a fixed origin o in the d-dimensional grid, we give a novel definition of digital rays dig(op) from o to each grid point p. Each digital ray dig(op) approximates the Euclidean line segment $\overline {op}$between o and p. The set of all digital rays satisfies a set of axioms analogous to the Euclidean axioms. We measure the approximation quality by the maximum Hausdorff distance between a digital ray and its Euclidean counterpart and establish an asymptotically tight Θ(log n) bound in the n×n grid. The proof of the bound is based on discrepancy theory and a simple construction algorithm. Without a monotonicity property for digital rays the bound is improved to O(1). Digital rays enable us to define the family of digital star-shaped regions centered at o, which we use to design efficient algorithms for image processing problems.