Surveying is the art of determining the relative positions of points on, above, or beneath the surface of the earth by means of direct or indirect measurements of distance, direction, and elevation.
Principles of Plane surveying:
There are two basic principles of surveying. These find their inherent applications in all the stages of a project, i.e., from initial planning till its completion.
To work from whole to part.
To locate a point by at least two measurements.
To Work from Whole to Part
It is the main principle of surveying and a method violating the principle of working from whole to part should not be adopted until and unless there is no alternative.
The main idea of working from whole to part is to localize the errors and prevent their accumulation. On the contrary, if we work from part to whole, the errors accumulate and expand to a greater magnitude in the process of expansion of survey, and consequently, the survey becomes uncontrollable at the end.
To Locate a Point by at Least Two Measurements
Two control points (any two important features) are selected in the area and the distance between them is measured accurately. The line joining the control points is plotted to the scale on the drawing sheet. Now the desired point can be plotted by making two suitable measurements from the given control points.