The normal map as a vector field

Thomas Waters, Matthew Alan Cherrie

Research output: Contribution to journalArticlepeer-review

19 Downloads (Pure)


In this paper we consider the normal map of a closed plane curve as a vector field on the cylinder. We interpret the critical points geometrically and study their Poincare index, including the points at infinity. After projecting the vector field to the sphere we prove some counting theorems regarding the winding and rotation index of the curve and its evolute. We finish with a description of the extension to focal sets of surfaces.
Original languageEnglish
Pages (from-to)145-157
JournalBalkan Journal of Geometry and Its Applications
Issue number2
Publication statusPublished - 18 Jun 2022


  • evolute
  • index
  • vector field
  • normal map
  • degree


Dive into the research topics of 'The normal map as a vector field'. Together they form a unique fingerprint.

Cite this