, Volume 15, Issue 2, pp 381–397 | Cite as

Efficient viewshed computation on terrain in external memory

  • Marcus V. A. AndradeEmail author
  • Salles V. G. Magalhães
  • Mirella A. Magalhães
  • W. Randolph Franklin
  • Barbara M. Cutler


The recent availability of detailed geographic data permits terrain applications to process large areas at high resolution. However the required massive data processing presents significant challenges, demanding algorithms optimized for both data movement and computation. One such application is viewshed computation, that is, to determine all the points visible from a given point p. In this paper, we present an efficient algorithm to compute viewsheds on terrain stored in external memory. In the usual case where the observer’s radius of interest is smaller than the terrain size, the algorithm complexity is θ(scan(n 2)) where n 2 is the number of points in an n × n DEM and scan(n 2) is the minimum number of I/O operations required to read n 2 contiguous items from external memory. This is much faster than existing published algorithms.


GIS External memory processing Viewshed Visibility maps 



This work was partially supported by CNPq—the Brazilian Council of Technological and Scientific Development, FAPEMIG—the Research Support Foundation of the State of Minas Gerais (Brazil) and by NSF grants CCR-0306502 and DMS-0327634 and by DARPA/DSO/GeoStar.


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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Marcus V. A. Andrade
    • 1
    • 2
    Email author
  • Salles V. G. Magalhães
    • 1
  • Mirella A. Magalhães
    • 1
  • W. Randolph Franklin
    • 2
  • Barbara M. Cutler
    • 3
  1. 1.DPIUniversidade Federal de ViçosaViçosaBrasil
  2. 2.ECSE Dept.Rensselaer Polytechnic InstituteTroyUSA
  3. 3.CS Dept.Rensselaer Polytechnic InstituteTroyUSA

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