The Model of the Digital Terrain Map (DTM)

The true digital terrain map (DTM) is needed to calculate so-called terrain gravity potential. It is one of the fundamental factors in earth geoid shape determination. There are many methods of calculation of the gravity potential. The gravity integral should cover all Earth area. There is no possibility to establish digital terrain map for whole planet. So it must be numerically proved, if the gravity integral converges to its extreme value for some limited part of the earth area. The model of DTM was established mathematically for testing a different way of gravity potential calculation. It contains all features of real DTM and has been build up in two steps processing.