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.