There are two methods available for finding the height of an object.
Tape and ranging rods method.
1.Tape and ranging rods method.:- This method is used where
the ground is level and the object is accessible. In the above picture PR be the object whose height to be determined. Where P be the peak and R be the base of the object. Two ranging rod W and U are fixed on the level ground at some distance from R. Two mark V and T marked on the ranging rod W and U. Looking through V and T mark the point Q on the PR. Then VW=TU=QR=h1. Sight the P from V so that S and P are in the same line. Measure the distance WU, WR and ST.
There are two triangles PQV AND STV formed.
PQ/QV=ST/TV
PQ= ST/TV*QV (Here TV=WU and WR=QV)
Thus PR= PQ+h1
2. Instrumental method:-
PROCESS:- Set the theodolite at O, levelled the instrument used plate level and altitude level. Measured the distance QR with the chain or tape. The angle of elevation A and angle of depression B also measure. Let the distance OR = D. Then use the tan formula.
h2 = D* TAN A
h3=D*TAN B
Total height of the PR : h2+h3
RL OF P= BM+h1+h2
RL OF Q= BM+h1-h2