Terrain Prickliness: Theoretical Grounds for High Complexity Viewsheds

Ankush Acharyya, Ramesh Jallu, Maarten Löffler, Gert Meijer, Maria Saumell, Rodrigo I. Silveira, Frank Staals, Hans Raj Tiwary

Research output: Chapter in Book/Report/Conference proceedingChapterAcademicpeer-review


An important task in terrain analysis is computing viewsheds. A viewshed is the union of all the parts of the terrain that are visible from a given viewpoint or set of viewpoints. The complexity of a viewshed can vary significantly depending on the terrain topography and the viewpoint position.
In this work we study a new topographic attribute, the prickliness, that measures the number of local maxima in a terrain from all possible angles of view. We show that the prickliness effectively captures the potential of terrains to have high complexity viewsheds. We present near-optimal algorithms to compute it for TIN terrains, and efficient approximate algorithms for raster DEMs. We validate the usefulness of the prickliness attribute with experiments in a large set of real terrains.
Original languageEnglish
Title of host publication11th International Conference on Geographic Information Science (GIScience 2021)
EditorsKrzysztof Janowicz, Judith A. Verstegen
PublisherSchloss Dagstuhl - Leibniz-Zentrum fuer Informatik
ISBN (Print)978-3-95977-208-2
Publication statusPublished - 2021

Publication series

NameLeibniz International Proceedings in Informatics (LIPIcs)
PublisherSchloss Dagstuhl--Leibniz-Zentrum fuer Informatik
ISSN (Print)1868-8969


  • Digital elevation model
  • Triangulated irregular network
  • Viewshed complexity


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