Computing Vertex Normals from Polygonal Facets

Grit Thürmer and Charles A. Wüthrich
Bauhaus-University Weimar

This paper appears in issue Volume 3, Number 1.
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Abstract

The method most commonly used to estimate the normal vector at a vertex of a polygonal surface averages the normal vectors of the facets incident to the vertex considered. The vertex normal obtained in this way may vary depending on the tessellation of the polygonal surface since the normal of each incident facet contributes equally to the normal in the vertex. To overcome this drawback, we extend the method so that it also incorporates the geometric contribution of each facet, consider the angle under which a facet is incident to the vertex in question.

Author Information

Grit Thürmer, Bauhaus-University Weimar, CoGVis/MMC Group99421 Weimar, Germany thuermer@medien.uni-weimar.de

Charles A. Wüthrich, Bauhaus-University Weimar, CoGVis/MMC Group99421 Weimar, Germany caw@medien.uni-weimar.de

Addendum

After publishing this paper, we have been made aware that the following work describes a similar technique: Séquin, C. H. “Procedural Spline Interpolation in UNICUBIX.” Proceedings of the 3rd USENIX Computer Graphics Workshop, Monterey CA, Nov. 1986, pp 63–83.

BibTeX Entry

@article{ThurmerWuthrich98,
  author = "Grit Thürmer and Charles A. Wüthrich",
  title = "Computing Vertex Normals from Polygonal Facets",
  journal = "journal of graphics, gpu, and game tools",
  volume = "3",
  number = "1",
  pages = "43-46",
  year = "1998",
}