[Proj] Distance calculations
Duncan Agnew
dagnew at ucsd.edu
Wed Oct 15 12:40:39 EDT 2008
The "down-under" paper that Cliff Mugnier refers to is available at
http://www.cage.curtin.edu.au/~will/thomas-featherstone.pdf
(At least I assume this is the one). The abstract states:
Vincenty’s (1975) formulas for the direct and inverse geodetic problems
(i.e., in relation to the geodesic) have been verified by comparing
them with a new formula developed by adapting a fourth-order
Runge-Kutta scheme for the numerical solution of ordinary differential
equations, advancing the work presented by Kivioja in 1971. A total of
3,801 lines of varying distances 10 to 18,000 km and azimuths (0 to
90°, because of symmetry) were used to compare these two very different
techniques for computing geodesics. In every case, the geodesic
distances agreed to within 0.115 mm, and the forward and reverse
azimuths agreed to within 5 microarcsec, thus verifying Vincenty’s
formula.
They reference Pittman but don't make any comparisons with his work.
The reference for that work is
Pittman, M. E. (1986). Precision direct and inverse solutions of the
geodesic, Surveying and Mapping 46(1), 47-54.
(which I wish Cliff Mugnier had cited) and for Kivioja is
Kivioja, L. A. (1971). Computation of geodetic direct and indirect prob-
lems by computers accumulating increments from geodetic line elements.
Bull. Geod. 99, 55-63.
This result would seem to settle the question for all practical (and
impractical) purposes, though a further comparison might be warranted.
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