What are the methods of distance measurement? Advantages and disadvantages of various methods

In summary, there are two major categories of methods: one, direct measurement; two, indirect measurement;

And direct measurement includes: 1, tape measure, 2, steel measuring tape, etc.;

Indirect measurement includes: 1, visual distance measurement, 2, visual interpolation measurement, 3, electromagnetic wave measurements, etc.;

The advantages of the direct measurement are: simple method; disadvantages: affected by the topography as well as the length and the limitations;

Indirect measurement has some advantages: not limited by the topography, low labor intensity, high efficiency; disadvantages: facility requirements. Limitations;

Indirect distance measurement has: not subject to terrain restrictions, low labor intensity, high efficiency; disadvantages: more facilities requirements.