Viewshed: Mapping Exactly What Can Be Seen From a Point
From a proposed tower, a scenic overlook or a watchtower, what is visible and what is hidden? A viewshed answers that by tracing lines of sight across the terrain, turning a single vantage point into a map of visibility.
The idea behind it
For an observer at a given location and height, a viewshed tests every other cell for an unobstructed line of sight over the intervening elevation surface, returning visible or not-visible (or a count, for many observers). It is a geometric query on the DEM rather than a spectral or statistical index.
How it is calculated
What the numbers mean
1 = in the line of sight from the observer · 0 = hidden. Cumulative viewsheds sum visibility from many points.
The data it needs
| Derived from | Digital Elevation Model (SRTM / Copernicus, 30 m) — not an optical band index. |
Where it is used
It is used in telecom and radar siting, wind-farm and infrastructure visual-impact assessment, scenic-value and tourism planning, and archaeology (inter-visibility of sites).
Limitations to know
Results are extremely sensitive to DEM error and to observer and target heights, and standard viewsheds ignore vegetation, buildings and Earth curvature unless you add them explicitly — a bare-earth viewshed can be badly optimistic in forested or urban settings.
Compute Viewshed on your own study area
Skip the code. Draw or upload a boundary and Spatial Research Suite runs Viewshed on live data — with cloud masking, exports and citations built in.
Run this analysis in GISforus →Frequently asked
What does a viewshed actually output?
A visibility map — which cells are in the observer's line of sight and which are hidden; cumulative viewsheds count visibility from many observer points.
Do viewsheds account for trees and buildings?
Not by default — a bare-earth DEM ignores them, so add surface features and Earth-curvature correction for realistic results.