Correct Answer - Option 2 : Undulating
The subtense tachometry method is adopted when the ground is Undulating.
- Tacheometry is a branch of angular surveying in which the horizontal and vertical distances are obtained by optical means as opposed to the ordinary process of chain and tape.
- This is done with the help of two special types of instruments- transit theodolite and stadia rod.
- The primary objective of this tacheometric surveying is to prepare contoured maps or plans requiring both horizontal as well as vertical control.
- It is used in reconnaissance surveys for highways, railways, etc.
Subtense tachometry method:
- The substance bar is an instrument used for measuring the horizontal distance between the instrument station and a station where the substance bar is to be set up. Subtense the method is an indirect method of distance determination. This method is consists of measuring the angle subtended by two ends of a horizontal rod of fixed length.