[Proj] Problems with Pittman geodesic??
OvV_HN
ovv at hetnet.nl
Mon Jan 19 13:16:38 EST 2009
Some time ago I referred to 2 articles by Saito.
He computes the geodesic problems by numerical integration. There are some
errors in the formulae, but his second article gives correct results for
'normal' values. Saito attends much detail to borderline situations, but
there are probably some errors in his descriptions.
Anyhow, he gives a couple of test points which everybody with geodesics code
definitively should try to replicate. You might be surprised!
Saito article 2 examples.
Using the formulas and the procedure described in the article, with an
equatorial radius of 6378388 meters and an inverse flattening of 297, the
following results were obtained. The computation was made in double
precision arithmetic - through twenty significant digits.
Line lat1 lat2 delta lon
1. 37d 19' 54.95367" 26d 07' 42.83946" 041d 28' 35.50729"
2. 35 16 11.24862 67 22 14.77638 137 47 28.31435
3. 01 00 00.00000 -00 59 53.83076 179 17 48.02997
4. 01 00 00.00000 01 01 15.18952 179 46 17.84244
5. 41 41 45.88000 41 41 46.20000 000 00 00.56000
6. 30 00 00.00000 37 53 32.46584 116 19 16.68843
7. 30 19 54.95367 -30 11 50.15681 179 58 17.84244
8. 00 39 49.12586 -00 45 14.13112 179 58 17.84244
9. 00 00 54.95367 00 00 42.83946 179 28 17.84244
Line dist. azim. back azim.
1. 4085966.7026 m 095d 27' 59.630899" 118d 05' 58.961609"
2. 8084823.8383 015 44 23.748498 114 55 39.921473
3. 19959999.9998 088 59 59.998971 091 00 06.118356
4. 19780006.5588 004 59 59.999957 174 59 59.884800
5. 16.2839751 052 40 39.390671 052 40 39.763172
6. 10002499.9999 045 00 00.000004 129 08 12.326009
7. 19989590.5480 002 23 52.108130 177 36 19.670109
8. 19994529.4446 177 39 39.010104 002 20 21.153036
9. 19977290.7711 054 08 27.731619 125 51 32.272327
From:
THE COMPUTATION OF LONG GEODESICS ON THE ELLIPSOID
THROUGH GAUSSlAN QUADRATURE
Tsutomu SAITO
Construction College,
Kodaira-shi Tokyo, 187 Japan.
Oscar van Vlijmen
----- Original Message -----
From: "Gerald I. Evenden" <geraldi.evenden at gmail.com>
To: "PROJ.4 and general Projections Discussions" <proj at lists.maptools.org>
Sent: Monday, January 19, 2009 2:57 AM
Subject: [Proj] Problems with Pittman geodesic??
> While checking out the accuracy of Vincenty vs. Pittman
> I was fairly consistently getting agreement to micron or
> better.
>
> BUT not always!!!
>
> I would appreciate anyone who has a Pittman geodesic routine
> to test the following inverse (WGS84 ellipsoid):
>
.....
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