Error term in pointwise approximation of the curvature of a curve

  • Authors:
  • Vincent Borrelli;Fabrice Orgeret

  • Affiliations:
  • Université de Lyon, CNRS UMR5208, Institut Camille Jordan, F-69622 Villeurbanne-Cedex, France;Université de Lyon, CNRS UMR5208, Institut Camille Jordan, F-69622 Villeurbanne-Cedex, France

  • Venue:
  • Computer Aided Geometric Design
  • Year:
  • 2010

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Abstract

Let P be a polygonal line approximating a planar curve @C, the discrete curvature k"d(P) at a vertex P@?P is (usually) defined to be the quotient of the angle between the normals of the two segments with vertex P by the average length of these segments. In this article we give an explicit upper bound of the difference |k(P)-k"d(P)| between the curvature k(P) at P of the curve and the discrete curvature in terms of the polygonal line's data, the supremums over @C of the curvature function k and its derivative k^', and a new geometrical invariant, the return factor@W"@C. One consequence of this upper bound is that it is not needed to know precisely which curve is passing through the vertices of the polygonal line P to have a pointwise information on its curvature.