[Proj] Environment variable et proj.4 vb wrapper

[Oscar van Vlijmen]

From: "Gheysen Thibaut"

... This is my first attempt to use proj4 and I don't know what I do wrong.
Here is the definition I use :
WGS 84 (epsg : 4326) : +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs
no_defs <> 
Lambert 72 Belge (epsg : 31370) : +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 +units=m +no_defs  no_defs <>

Reply:

I don't do PROJ command lines, but it seems to me that you first have to
perform a datum transform from WGS84 to International for Belgium. This
can't be evoked with the epsg:4326 init since it has no transform
parameters. Find the complete transform parameters, check rotation model and
direction (from/to), supply the command line with a proper datum transform,
then project.

Belgium 1972 to WGS84:
translation in m, rotation in arcsec, scale in ppm.
Position vector rotation (PROJ)
dx=-99.059; dy=53.322; dz=-112.486; rx=0.419; ry=-0.83; rz=1.885; ds=-1.00;
Derived from ESRI ArcGIS parameters.

Going in the other direction, from wgs to intl, just negate all parameters.