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Analyze Visibility

You can analyze the viewshed of a functional surface to determine visibility in different areas.

What is the viewshed?

The viewshed identifies the cells in an input raster that can be seen from one or more observation points or lines. Each cell in the output raster receives a value that indicates how many observation points can see the location. If you have only one observation point, each cell that can be seen from the observation point is given a value of 1. All cells that can't be seen from the observation point are given a value of 0.

Why calculate the viewshed?

The viewshed is useful when you want to know how visible objects might be—for example, you may need to know the answer to questions such as, From which locations on the landscape will the landfill be visible if it is placed in this location? What will the view be like from this road? or Would this be a good place for a communications tower?

In the example below, the viewshed from an observation point is identified. The elevation grid displays the height of the land (darker locations represent lower elevations), and the observation point is marked as a green triangle. Cells in green are visible from the observation point, while cells in red are not.

Elevation grid
Elevation grid with visibility analysis

Displaying a hillshade underneath your elevation with the output from the viewshed function gives a realistic impression of the landscape and clearly indicates what locations an observer can see from the observation point.

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