The knowledge of visibility information on a terrain is essential for a large number of current applications. There exist several algorithms in the literature for building visibility maps (VMs) but only for one single viewpoint or at most for a very small number of observers. This limitation is due to the high computational complexity of the used methods (which is greater than O(N2), where N is...

We describe several programs working with 1201x1201 gridded (array) terrain elevation data: determining the viewshed of an observer, and the visibility indices of all points, converting from a grid to a TIN, losslessly and lossily compressing a grid, and interpolating from contours to a grid. The intent is to integrate these, and new, programs, into a test suite the better to understand hypsogr...

We describe several programs working with 1201x1201 gridded (array) terrain elevation data: determining the viewshed of an observer, and the visibility indices of all points, converting from a grid to a TIN, losslessly and lossily compressing a grid, and interpolating from contours to a grid. The intent is to integrate these, and new, programs, into a test suite the better to understand hypsogr...

With the increased availability of user generated data, assessing the quality and credibility of such data becomes important. In this article, we propose to assess the location correctness of visually generated Volunteered Geographic Information (VGI) as a quality reference measure. The location correctness is determined by checking the visibility of the point of interest from the position of t...

Solar Radiation is considered as an important parameter in modeling environmental, hydrologic and biophysical processes. One of the reasons that solar radiations are not extensively used in models is the problem of its measurement in different points. Solar Analyst Viewshed Algorithm makes possible calculation of the topographic effects on solar radiation at local and landscape scales. With res...

introduction conservation and management of landscapes and beautiful sceneries is one of the necessities of establishing and maintaining the protected areas. analysis of landscape visual quality has an important place in landscape planning and designing. in this way, reviewing effective criteria and discovering the simple patterns which affect the landscapes is the most important step of modeli...

The advantages of using the fundamental topographic features of a surface namely the peaks, pits, passes, ridges and channels as the observers (viewpoints) in visibility computation is presented. Considerable time can be saved without any significant information loss by using the fundamental topographic features as observers in the terrain. This optimisation is achieved because of a reduced num...