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Visibility and Dead‐Zones in Digital Terrain Maps
Author(s) -
Or Daniel Cohen,
Shaked Amit
Publication year - 1995
Publication title -
computer graphics forum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 120
eISSN - 1467-8659
pISSN - 0167-7055
DOI - 10.1111/j.1467-8659.1995.cgf143_0171.x
Subject(s) - terrain , visibility , representation (politics) , digital elevation model , computer science , computer graphics (images) , surface (topology) , viewshed analysis , terrain rendering , triangulated irregular network , computer vision , elevation (ballistics) , artificial intelligence , visualization , geometry , geography , mathematics , remote sensing , cartography , politics , meteorology , political science , law
The problem of detecting the visible and hidden areas of a topographic surface from a given viewpoint is well known, and has applications in GIS and other fields. The computational geometry literature is rich with solutions based on a polygonal representation of the surface. This work confronts the problem by working directly on the Digital Elevation Map which represents the terrain surface. We present an algorithm that processes discrete lines of sight from the viewpoint to the surface perimeter, and tests the unit‐sized terrain elements along the discrete cross‐sections defined by these lines. The algorithm is very efficient, performing O(n) testing operations, consisting of a few additions and no more than one multiplication each, where n is the number of the terrain elements in the map.