a quick method
adopted for large surveys only
most accurate method
suitable for hilly terrains
ranging
centring
horizontal control
vertical control
only (i)
(i)and(ii)
(ii) and (iii)
(i), (ii) and (iii)
direct method
square method
cross-sections method
tacheometric method
Contour interval on any map is kept constant.
Direct method of contouring is cheaper than indirect method.
Inter-visibility of points on a contour map cannot be ascertained.
Slope of a hill cannot be determined with the help of contours.