Level-Loop Misclosure Distribution (Compass Rule)
Spreads a level-loop misclosure back across the benchmarks so the loop closes.
Example
You enter
- Elevs 105.2, 108.6, 100.05
- Dists 500, 800, 700
- Known closing elevation (ft) 100
You get
- Misclosure 0.05
- Total dist 2000
- Last adjusted 100
Details, formula, and sources
Correction to each point = -misclosure x (distance leveled to it / total distance) - the vertical analog of the compass rule a traverse adjustment uses. A three-leg loop closing 0.05 ft high over 2,000 ft puts -0.0125 ft on the first point at 500 ft and the full -0.05 ft on the last, so the adjusted elevations land exactly on the known benchmark. Distance-weighted; equal-weight-per-setup is an alternative. A computational aid; the project control governs.
misclosure = last_elev - known_close; cum_i = sum(dists[0..i]); correction_i = -misclosure x cum_i / cum_total; adjusted_i = elev_i + correction_i.
The compass-rule (distance-weighted) distribution of a level-loop misclosure, the vertical analog of the horizontal compass rule, as compiled in the standard surveying references (Ghilani/Wolf, Elementary Surveying), by name.
The compass-rule adjustment is a public surveying result; FM 5-233 (Construction Surveying) is a public-domain US Government reference.
Estimate. AHJ and licensed professional govern.
Field names used by the API: elevs, dists, known_close, misclosure, total_dist, last_adjusted
- Distance weighting correction proportional to the cumulative distance leveled to each point; the last point takes the full misclosure and closes exactlycompass rule (Ghilani/Wolf)
- Single loop one continuous level run with corrected rod readings; a network needs a least-squares adjustmentscope of this tile