The basics of visibility analysis
The aim of visibility analysis is to produce a coverage of an area that can be seen from a specified location. This coverage is called a viewshed, which is why the terms visibility analysis and viewshed analysis are used interchangeably. To perform a simple visibility analysis, you need to define at least two components:
Observation point: A point that represents an observer's position and for which visibility is being analyzed
DEM: This represents irregularities in the earth's surface and is used to examine visibility along the line of sight
The idea underlying the process of this analysis is to compare the height of the observation point against the height of earth's surface point along the given line of sight. If the height of the surface point is less than that of the observation point, then it will be seen from the current position; if it is higher, the visibility line will be blocked. Similarly, all points within a certain radius are compared against...
