Extending the applicability of viewsheds in landscape planning

Abstract

There follows a summary of the proposed variants, and a re~h~ determination of the visible area or viewshed from a view of their sensitivity to database error. Finally, a discusviewing point looking out on a landscope is a widely availa- sion of how these variants may be used to respond to the ble function in a GIS. A reconsideration of the oueries which queries is presented. ma; be made of the viewshed, however, reveal; that often the function does not address them correctly. This has led to the specification of alternative viewshed functions intended to give flexible outcomes which can be used to respond to the queries directly. The alternatives include the horizons viewshed, the local offset viewshed, the global offset viewshed, and reverse viewing versions of all three. Applications of these alternative viewshed functions to answer queries about the landscape and the view which the binary viewshed is not able to respond to either precisely or flexibly are examined.