Citlivostní analýza vyhodnocení viditelnosti z linie v ArcGIS

Abstract

This thesis addresses the analysis of the visibility of lines in ArcGIS, evaluates and proposes a solution to its problem. Viewshed evaluates only the visibility of nodes and vertices on the line. Therefore in some cases, if the vertices are farther away, the results of analysis of visibility is inaccurate. Some areas were evaluated as invisible despite the fact that they are visible in real. Viewshed is computed by merging the viewshed outputs for every vertex. As a consequence it is influenced by the number and the distribution of the vertices. The analysis (two – factor ANOVA) was revealed that the visible area depends on the spacing of the observer line vertices and on the DEM grid resolution. The VIELYNE tool was created in purpose of finding the optimal parameters for viewshed analysis and takes into account both the spacing of the vertices and the raster resolution. The ANOVA results confirmed the dependence of the visible area on the input parameters (DEM resolution, vertex spacing of observer line). As an additional output of the sensitivity analysis, the time period of the calculation was monitored.