Line-of-sight has important application value in navigation, aviation, and military fields, such as setting up radar stations, television transmission stations, road selection, and maritime navigation. In military contexts, it is used for positioning artillery, setting up observation posts, and laying communication lines. Sometimes it may also be necessary to analyze invisible areas; for example, low-altitude reconnaissance aircraft must avoid enemy radar detection as much as possible and choose to fly in radar blind zones. The basic content of line-of-sight includes two aspects: one is the visibility analysis between two or more points; the other is the viewshed, which analyzes the area covered by the view for a given observation point.
Viewshed
The viewshed is the surface area visible from one or more observation points. A viewshed is computed on a raster data set for a given observation point, based on a certain relative height, to find the area within a specified range that is visible from the observation point—that is, the line-of-sight coverage area of the given point. The analysis result is a raster dataset. Viewshed analysis is used when determining the location of transmission towers, radar scanning areas, and setting up forest fire lookout towers. Viewshed has relatively broad applications in navigation, aviation, and military fields.
Visibility Analysis
SuperMap surface analysis provides two-point visibility analysis and multi-point visibility analysis functions, depending on the number of observation points.
Two-point visibility analysis is used to analyze whether any two points on a raster surface can see each other.
Multi-point visibility analysis is used to analyze whether multiple points on the surface of the grid can see each other.
Note
- If performing terrain visibility or viewshed analysis in a 3D scene, the analysis can only ensure correct results when the "terrain scale factor" is set to 1.