[Proj] Belge 1972 / Belgian Lambert 72 (31370) - towgs84 parameters

[Thibaut Gheysen]

Hi,

I have a problem in QGIS 1.4.0 when I reproject a gpx file into Belgian
lambert 72 coordinate system : the waypoints are not correctly placed on the
map (see this image :
http://www.fsagx.ac.be/gf/outilslogiciels/Garbel/proj4.jpg). I already have
a similar problem when writing a GPS software (
http://lists.maptools.org/pipermail/proj/2006-August/002447.html). To solve
this I have used this towgs84 parameters :
+towgs84=-99.059,53.322,-112.486,0.419,-0.83,1.885,-0.999999. In QGIS, the
towgs84 parameters are different
(+towgs84=106.869,-52.2978,103.724,-0.33657,0.456955,-1.84218,1). When I use
my GPS software to reproject into Belgian Lambert 72 the waypoints are
correctly placed (red points in the image) but not when I use QGIS (yellow
points). I think thus there is a problem in the epsg 31370 definition.

Best regards,
Thibaut.
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