The Create Viewshed tool uses the Esri Elevation Analysis service to determine which areas are visible from specified observer points.
A GIS analyst is performing a preliminary review of wind farm applications to determine which proposals should be submitted for further assessment. Her criteria are that the proposals must have road access and cannot be on or within view of protected areas. Create Viewshed can be used to determine which proposals are within view of the protected areas.
A single input of point features is required. The points can be loaded through the input drop-down menu or created using the Draw tool.
Visibility settings are used to set the height of the observer, the height of the observed features, and the maximum viewing distance of the observer. The settings may be in Miles, Yards, Feet, Kilometers, or Meters. The default value will be based on the Units setting in your profile.
Height of observer locations
6 Feet (US Standard setting) or 1.75 Meters (Metric setting)
The height of the observer locations above the ground. Examples of observer locations include people and fire towers.
Height of other objects on the ground
0 Feet (US Standard setting) or 0 Meters (Metric setting)
The height of the objects being viewed by the observer. This height will be added to the height of the terrain to establish visible areas. Examples of objects on the ground include people, wind turbines, and the ground itself.
Maximum viewing distance
9 Miles (US Standard setting) or 15 Kilometers (Metric setting)
The cutoff distance where the computation of the visible areas stop, regardless of terrain, observer height, and object height. The maximum viewing distance is 31 miles (50 kilometers).
The results are the areas where the observers can see the observed objects. The frequency field records the number of observer points that can see each area.
If Use current map extent is checked, only the observer points that are visible within the current map extent will be analyzed. If unchecked, all observer points in the input layer will be analyzed, even if they are outside the current map extent.
- The input must be point features.
- Viewing distance can be no more than 31 miles (50 kilometers).
- All observers must have the same height. All objects on the ground must also have the same height.
- The visibility does not include obstructions such as trees and buildings.
How Create Viewshed works
The Create Viewshed tool uses a digital elevation model (DEM) from the Esri Elevation Analysis service. The resolution of the DEM used will depend on the location of the analysis and will be recorded in the DEMResolution field of the result layer.
Use Create Viewshed to determine the visible area from specified observer points. Other tools may be useful in solving similar but slightly different problems.