Principles of Surveying
Followings are the principles of surveying which should be kept in mind while determining the relative positions of points on the surface of earth:
To work from whole to part
Working from whole to part is done in surveying in order to ensure that errors and mistakes of one portion do not affect the remaining portion. First step in the extensive surveys such as topographic surveys, is to establish a system of control points with high precision. For the horizontal control, the points are established by triangulation or precise traversing. To do this by triangulation, the area to be surveyed are divided in to large triangles. These triangles are surveyed with greatest accuracy. These large triangles are further divided in to small triangles which are surveyed with less accuracy. The object of this system is to prevent the accumulation of errors, and to control minor errors.
On the other hand if we work from part to whole, small errors are magnified in the process of expansion of survey. These errors become uncontrollable at the end.
Fix the positions by two independent process
To fix the positions of new stations by two independent process. The new stations are fixed from points already fixed by linear measurements, angular measurements or by both linear and angular measurements.
Surveying and leveling by T.P.Kanetkar