Free Web Tool

Three-Point Resection

Locate an unknown station P from three known stations and two observed angles using Tienstra’s barycentric formula.

Inputs

Point A: N

Point A: E

Point B: N

Point B: E

Point C: N

Point C: E

α (∠APB, deg)

β (∠BPC, deg)

Method — Tienstra

Compute auxiliary K_A = (cot ∠A − cot α)·... Tienstra's formula gives barycentric weights.
P_N = (W_A·N_A + W_B·N_B + W_C·N_C)/(W_A+W_B+W_C); same for E.
Used by surveyors for free-station / resection orientation.

Results

Angle ∠A—

Angle ∠B—

Angle ∠C—

Weight WA / WB / WC—

P (N, E)—