What is the status of lib/gis/datumtransform.table ? Trying to do some
reprojection between LL-WGS84 (epsg 4326) and belgian lambert 72
(epsg:31370), I see some problems due to the parameters in that file:
- in the proj epsg file (Rel. 4.6.0, 21 Dec 2007), the belgian lambert
72 projection is defined as
+proj=lcc +lat_1=51.16666723333333 +lat_2=49.8333339 +lat_0=90
+lon_0=4.367486666666666 +x_0=150000.013 +y_0=5400088.438 +ellps=intl
+towgs84=106.869,-52.2978,103.724,-0.33657,0.456955,-1.84218,1 +units=m
+no_defs
- this is confirmed by the info given by the Belgian geographic
institute [1], which gives the same parameters with only differences in
sign of which I don't know if they have any effect
- however in lib/gis/datumtransform.table one can find:
bel72 "towgs84=-99.1,53.3,-112.5,0.419,-0.830,1.885,-1.00" "Belgium"
"Accuracy about 0.3m"
which gives quite different results when reprojecting compared, for
example, to cs2cs.
What is the reason to have this datumtransform.table file ? Isn't most
of this covered by proj / epsg these days ?
Moritz
[1] http://www.ign.be/FR/FR2-1-2.shtm (bottom of the page)
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