The tangential method of tacheometry is being used when stadia hairs are not present in the diaphragm of the instrument or when the staff is too far to read.

In this method, the staff sighted is fitted with two big targets (or vanes) spaced at a fixed vertical distances. Vertical angles corresponding to the vanes, say q₁ and q₂ are measured. The horizontal distance, say D and vertical intercept, say V are computed from the values s (pre-defined / known) q₁ and q₂ . This method is less accurate than the stadia method.

<< Back | Next >>