How do I obtain the height of the terrain through longitude and latitude, or is there any method for attaching ground lines? When I pass radiographic testing, the height of the terrain will change depending on the elevation level. Therefore, I feel that the method of radiographic testing is unreliable
It depends on what you mean by “height” of the terrain. Do you need the height of the terrain relative to the WGS84 ellipsoid? Or do you need the height of the terrain above sea level?
In any case, here are a couple of forum threads with similar questions. They may be applicable to your use case.