The 3D viewshed calculates and marks all areas on the terrain and on 3D models and objects that are visible from a selected point on the terrain.
Create/edit a viewshed:
- On the sidebar > > Tools tab > Viewshed.
- In the 3D Window, click to define your viewpoint for the 3D viewshed, and then click again to define your desired endpoint (defining the distance of sight). The viewshed appears on the terrain as a sector of a circle, where the center point is the viewpoint and the arc is the endpoint (marking the end of the distance of sight analysis). Within the sector, areas that are visible from the viewpoint are colored green, whereas areas that are not visible from the viewpoint are colored red. The 3D viewshed is saved and is available from side toolbar > > Project Tree tab > My Data section.
- After creating a viewshed, the property sheet opens to set its properties.
- Description - The description or name of the 3D viewshed. This text appears in the Project Tree as the name of the object.
- Altitude - The altitude above the ground for the viewer location.
- Field of View - The angle limits of the viewshed, in degrees.
- Distance - The length of the viewshed analysis from the viewer in meters.
- Direction - The horizontal angle of the camera when viewing the viewer location.
- Visibility Distance - The distance from the camera at which the viewshed disappears.
- The initial viewshed is for preview only. Once you have adjusted the properties as required, if you want to generate a precise viewshed, click Calculate.
- Set some additional properties:
- Spacing - Distance between each of the rays that is sampled. The lower the value, the more accurate the viewshed but the longer it takes to calculate.
- Set Viewer Altitude - To set an altitude above the ground for the viewer location, enable this option, and then set the Viewer Altitude.
- Target Altitude - Sets the required altitude for the target.
- Click Calculate. The 3D viewshed is saved and is available in the My Data section of the Layers panel.