4. Survey Computations
Survey Computations
This domain tests coordinate geometry, bearings, distances, intersections, resections and area computations. The exam checks whether you can choose the correct formula, keep quadrant signs, and present results with sensible precision.
Core rules
- Bearings are measured clockwise from north; reduce to 0-360 degrees.
- From coordinates: dE = E2 - E1, dN = N2 - N1; distance = sqrt(dE^2 + dN^2); bearing = atan2(dE, dN).
- Area by coordinates: 2A = sum(Ei x Ni+1 - Ei+1 x Ni), taken as absolute value.
- Intersections require checking geometry; near-parallel lines produce weak solutions.
- Carry extra digits in computation and round only the final answer.
Worked example
A = (1000.000 E, 1000.000 N), B = (1100.000 E, 1050.000 N). dE = 100.000, dN = 50.000. Distance = sqrt(100^2 + 50^2) = sqrt(12,500) = 111.803 m. Bearing = atan2(100, 50) = 63.4349 degrees = 63 degrees 26 minutes 06 seconds. Because dE and dN are both positive, the bearing lies in the northeast quadrant; no quadrant correction is needed.
Traps
Using atan(dE/dN) without quadrant logic; reversing dE and dN; rounding intermediate coordinates; reporting area in wrong units; accepting an intersection with a tiny cut angle.