Singleviewshed

Singleviewshed is a spatial analysis concept used in geographic information systems to determine which parts of a terrain are visible from a single observer location. It computes a visibility map based on a digital elevation model (DEM) and an observer’s height, producing a dataset that marks areas visible from that point.

Methodology and outputs: The analysis performs line-of-sight checks from the observer to every location within the study area, comparing terrain elevations along each sightline. It accounts for the observer height and, in some implementations, target height, maximum distance, and optional atmospheric or curvature effects. The typical outputs are a raster or vector layer that designates visible versus non-visible cells or areas, sometimes augmented with distance, angle, or horizon information.

Inputs and parameters: Required inputs include a DEM, the observer’s location (often as a point) and the observer height. Optional parameters commonly supported are target height, maximum range, azimuth constraints, and resolution. The method assumes bare-earth terrain unless additional data (such as buildings or vegetation layers) are incorporated to modify elevations.

Applications and use cases: Singleviewshed supports siting of communication towers, surveillance or sensor networks, urban and rural planning, landscape management, and environmental impact assessments. It helps evaluate sightlines for tourism or safety planning and informs decisions about land use and infrastructure layout.

Limitations and considerations: Results depend on the accuracy and resolution of the DEM and typically represent static conditions. Vegetation, buildings, seasonal changes, and atmospheric effects may not be fully captured unless explicitly modeled. For multiple viewpoints, separate singleviewshed analyses are often combined into more complex visibility studies. Related concepts include multi-viewshed and horizon analysis.