Definition and requirements of height difference

Elevation between two points, route calculation formula, overlap, etc. The elevation difference is the elevation difference between two points, that is, the end elevation minus the starting elevation. Requirements are: route calculation formula, coincidence degree, deflection angle, aerial survey scale selection, multi-image space forward intersection, control point layout, control point accuracy and other 2 1 requirements. According to the different datum, the height can be divided into: absolute height; Relative height; True height; Photography flies high.