This tool can be used to calculate a measure of landscape visibility based on the topography of an input digital elevation model (DEM). The user must input DEM a (`dem`), the viewing height (`height`), and a resolution factor (`res_factor`). Viewsheds are calculated for a subset of grid cells in the DEM based on the resolution factor. The visibility index value (0.0-1.0) indicates the proportion of tested stations (determined by the resolution factor) that each cell is visible from. The viewing height is in the same units as the elevations of the DEM and represent a height above the ground elevation. Each tested grid cell's viewshed will be calculated in parallel. However, visibility index is one of the most computationally intensive geomorphometric indices to calculate. Depending on the size of the input DEM grid and the resolution factor, this operation may take considerable time to complete. If the task is too long-running, it is advisable to raise the resolution factor. A resolution factor of 2 will skip every second row and every second column (effectively evaluating the viewsheds of a quarter of the DEM's grid cells). Increasing this value decreases the number of calculated viewshed but will result in a lower accuracy estimate of overall visibility. In addition to the high computational costs of this index, the tool also requires substantial memory resources to operate. Each of these limitations should be considered before running this tool on a particular data set. This tool is best to apply on computer systems with high core-counts and plenty of memory.

## See Also

viewshed

## Function Signature

`def visibility_index(self, dem: Raster, station_height: float = 2.0, resolution_factor: int = 8) -> Raster: ...`

## Project Links

WbW Homepage User Manual Support WbW