wrong proj4text in spatial_ref_sys for SRID 31300 and 31370
|Reported by:||maesen.karel||Owned by:|
The proj4text field for the Belgian Lambert72 CRS'es in the spatial_ref_sys table is incorrect (srid=31370 and 31300). Neither entry has the required datum transformation instruction.
Belgian Lambert72 uses the BD72 datum and not WGS84. Due to the missing datum transformation instruction, transforming from Lambert72 to WGS84 in Postgis results in geographic coordinates relative to the BD72 datum, in stead of WGS84. This results in deviations in the order of 100-200 meter.
I believe that the following string needs to be added to the proj4text: +towgs84=-106.868628,52.297783,-103.723893,0.336570,-0.456955,1.842183,-1
See the page at http://www.ngi.be/NL/NL4-4.shtm for reference. (Note that the parameters indicated on this page are from ETRS89 to BD72. They need to be inversed for the +towgs84 instruction. )