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. The defined viewshed is initially displayed in Preview mode. After setting viewshed parameters and repositioning the viewshed as necessary, a high quality viewshed can be calculated and displayed.
- On the sidebar > Analysis 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 defined viewshed is initially displayed in Preview mode. Generally, you will want to set viewshed parameters (step 4) and reposition the viewshed as necessary, before calculating a high quality viewshed (step 5). 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 the Objects section of the sidebar’s Analysis tab.
- Click Viewshed Properties to set its properties. Click Move Horizontally or Move Vertically to reposition the viewshed.
- To calculate a high quality viewshed, click Calculate . After all viewshed data is downloaded from the server and calculations are complete, the viewshed is redisplayed with a high degree of precision. The intensity of the viewshed colors is increased to indicate that you are in Calculated mode, and the Calculate button appears dimmed. Note that you can recalculate at any point.
Note: If changes are made to a viewshed (e.g. properties are modified, or its position is adjusted), the viewshed switches back to Preview mode.