Viewsheds are areas of terrain visible from a specific location, such as a mountain, building, or observation point. They are commonly used in landscape analysis and urban planning to determine which areas are visible or not visible from a particular viewpoint.
Viewsheds are applied in various areas, including natural resource assessment, such as identifying areas with high visual quality for ecotourism or determining critical visual habitat areas for endangered species. They are also used to analyze the visibility of a point of interest or an object within a specific geographic area, assisting in decisions about the placement of specific projects like telecommunications antennas, military lookout posts, and urban viewpoints. Furthermore, they are applied in bird watching and other activities requiring detailed visibility analysis in a geographical space.
Several tools are available for viewshed analysis. In this example, the “Geodesic Viewshed” tool is used, located at:
Geoprocessing > Toolboxes > Spatial Analyst Tools > Surface > Geodesic Viewshed
Configuring the Geodesic Viewshed Tool
To configure the “Geodesic Viewshed” tool, use the “DEM.tif” file as the input raster. The following parameters must be set:
- Input raster: Select the DEM as input.
- Input point or polyline observer features: Select a layer of points or lines from which to create the viewshed. This point can also be drawn directly on the map by clicking the pencil icon.
- Output raster: Select the directory or geodatabase where the resulting raster layer will be stored.
- Target device for analysis: Choose the use of the GPU, CPU, or both for conducting the analysis.
- Advanced configuration: The “Viewshed parameters” section allows customization of how visible areas are calculated, while “Observer parameters” define properties of the observation point, such as the observer’s height above the ground.
Configuration of the “Geodesic Viewshed” tool.
Interpreting the Viewshed Output
The output of the tool is a raster image where visibility from the observation point is represented. The observer’s location is marked (typically in blue), and the visible areas from that point are highlighted (commonly in green). This visual representation allows users to understand how terrain features obstruct or reveal visibility across the landscape.
Viewshed generated with the “Geodesic Viewshed” tool.
How to Check Raster Resolution in ArcGIS Pro
To check the resolution of a raster file in ArcGIS Pro, right-click on the raster layer in the “Contents” panel and select “Properties.” Then, navigate to the “Source” tab and find the resolution details in the “Raster Information” section under “Cell Size X” and “Cell Size Y.”