METHODS OF CONTOURING
Contouring requires the determination of elevation of different points on the ground and at the same the horizontal positions of those points should be fixed. Levelling work is carried out to exercise vertical control and simultaneously to exercise horizontal control compass survey or chain survey or plane table survey is to be carried out. If the theodolite is used horizontal and vertical both controls can be achieved from the same instrument. One can classify the contouring in different groups based on the instruments used.
However, broadly speaking there are two methods of surveying which is following:
- Direct methods
- Indirect methods.