是程序计算从选定的点的地形图的可见性。我..

代码说明：

这个程序可以计算给定点处的小区信号范围覆盖。-is program computes a map of visibility from a selected point on a topography. It has been written to help the search for radio relay best location. Because it considers only direct line of sight, it gives a good estimation for possible radio link for short distances only (less than 10 km), neglecting curvature of the Earth, Fresnel zone and atmospheric refraction on radio waves propagation. The program computes the relative elevation angle of the mask for each point (the angle is null or negative if the point is visible). The function needs a digital elevation model Z and associated (X,Y) vectors or matrices of coordinates (same unit as Z), position of the point (X0,Y0), the antenna height H0 (for instance 4 m), and the hypothetic antenna height Ha on each topography points (for instance 3 m). When no output argument is given, the function plots a map of the results (color map of mask angles, and blank for visible points, see example screenshot). The s