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Resection
Resection Simulation
Resection Summary
Resection
This method is a little different in that the stand point is unknown, and three directions are measured to three known features. Commonly used by bushwalkers for position fixing, but also capable of high accuracy when appropriate equipment is used. Reduced using fundamental triangle geometry, or more easily with Tienstra's formula:
| k1 = | 1 | k2 = | 1 | k3 = | 1 |
| Cot A - Cot a | Cot B - Cot b | Cot C - Cot c |
| EP = | K1EA + K2EB + K3EC | NP = | K1NA + K2NB + K3NC |
| K1 + K2 + K3 | K1 + K2 + K3 |
Watch how the angles are named when changing the geometry of the field observations. Alpha, beta and gamma are observed, A B and C are obtained from the coordinates of the known points.
The full derivation of this can be found in Bannister, Raymond and Baker, Surveying, Chapter 7: Survey Methods, 6th Edition, p190.