Survey Measurement and Computations
This domain tests closing, adjusting, and reporting measurements so the numbers you deliver are defensible.
Traverse and adjustment
Close the angular work first, distributing angular error under an accepted rule, then compute latitudes and departures and assess linear misclosure. Precision is the ratio of misclosure to perimeter, e.g., 0.20 ft in 5,000 ft = 1:25,000. The compass (Bowditch) rule distributes misclosure proportional to course length; the transit rule distributes it proportional to the latitude or departure magnitudes. Least squares is preferred where redundant observations and realistic weights exist.
Coordinates and area
Area by coordinates uses the shoelace formula: sum of x_i·y_(i+1) minus y_i·x_(i+1), halved. Double meridian distances give the same result. Report area in square feet and acres (43,560 ft² per acre).
Worked example
A rectangle has coordinates (0,0), (200,0), (200,150), (0,150). Shoelace sum = (0·0 + 200·150 + 200·150 + 0·0) − (0·200 + 0·200 + 150·0 + 150·0) = 60,000; area = 30,000 ft². 30,000 ÷ 43,560 = 0.689 acre.
Traps
Closing bearings but not horizon; reporting precision as a raw misclosure; mixing bearings and azimuths in the same table; sign errors in latitudes and departures; mixing feet and meters; rounding intermediate coordinates so the area changes in the last digits.