Projection
Corrections for lines drawn on a map projection.
This group covers corrections that come from projecting the curved Earth onto a flat grid. The arc-to-chord correction is the small angle between a line's straight grid bearing and the curved line it represents, in UTM or a state plane zone. Surveyors running long traverses or precise azimuths on a grid use it. The pitfall is ignoring it on long lines far from a zone's center, where it grows.
I want to correct a grid bearing for the curve of the projected line
- Arc-to-chord correction (t − T)
The small angle between a line's straight grid bearing and its curved projected geodesic, at each end, in UTM or a State Plane zone, with the grid and ellipsoid distances.