A Study on the Viewshed Computation
Two algorithms for the viewshed computation, the Bensenham method and the fixed interval method, are implemented in this study. Differences between these two algorithms and the software implemented in the GIS packages, namely, ARC/INFO (visibility) and GRASS (r.los), are evaluated with real terrain data sets. Six indices are used to measure the similarity between the viewshed computed from different algorithms. The concept of binary, probable and fuzzy viewshed are also investigated and experimented. It is found that there are apparent differences between different algorithms/software implementations. Comparing with binary viewshed, the probable viewshed computed with added simulated elevation error, provides higher correlation between different algorithms.
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