Known values:
Baseline distance AB length, height h1 of the observer at points A and B.
Vertical angles measured at A – α1, a2 and δ.
Vertical angles measured at B – β1 and β2.
Solution: Height of object Η.
First, measure horizontal distance AB and vertical angles α1, α2, δ and β1, β2 from observer points A1 and B1 respectively.
In triangle A1ΕB1,
Same for triangle A1OB1,
Then calculate sloping distance A1Ε:
and
Same for sloping distance A1O:
and
Then:
Thus:
