caa a22 4500 445331976 CHVBK 20180317142740.0 cr unu---uuuuu 170323e20110401xx s 000 0 eng 10.1007/s10707-009-0100-9 doi (NATIONALLICENCE)springer-10.1007/s10707-009-0100-9 Efficient viewshed computation on terrain in external memory [Elektronische Daten] [Marcus Andrade, Salles Magalhães, Mirella Magalhães, W. Franklin, Barbara 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. Springer Science+Business Media, LLC, 2009 GIS nationallicence External memory processing nationallicence Viewshed nationallicence Visibility maps nationallicence Andrade Marcus DPI, Universidade Federal de Viçosa, Viçosa, Brasil aut Magalhães Salles DPI, Universidade Federal de Viçosa, Viçosa, Brasil aut Magalhães Mirella DPI, Universidade Federal de Viçosa, Viçosa, Brasil aut Franklin W. ECSE Dept., Rensselaer Polytechnic Institute, Troy, NY, USA aut Cutler Barbara CS Dept., Rensselaer Polytechnic Institute, Troy, NY, USA aut GeoInformatica Springer US; http://www.springer-ny.com 15/2(2011-04-01), 381-397 1384-6175 15:2<381 2011 15 10707 https://doi.org/10.1007/s10707-009-0100-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10707-009-0100-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Andrade Marcus DPI, Universidade Federal de Viçosa, Viçosa, Brasil aut NATIONALLICENCE 700 1- Magalhães Salles DPI, Universidade Federal de Viçosa, Viçosa, Brasil aut NATIONALLICENCE 700 1- Magalhães Mirella DPI, Universidade Federal de Viçosa, Viçosa, Brasil aut NATIONALLICENCE 700 1- Franklin W. ECSE Dept., Rensselaer Polytechnic Institute, Troy, NY, USA aut NATIONALLICENCE 700 1- Cutler Barbara CS Dept., Rensselaer Polytechnic Institute, Troy, NY, USA aut NATIONALLICENCE 773 0- GeoInformatica Springer US; http://www.springer-ny.com 15/2(2011-04-01), 381-397 1384-6175 15:2<381 2011 15 10707 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer