[Proj] Datum shifts in PROJ's EPSG table (The Netherlands and Belgium)

Roger Oberholtzer roger at opq.se
Thu Nov 2 09:27:59 EST 2006

On Thu, 2006-10-26 at 16:17 +0200, Oscar van Vlijmen wrote:

> I suppose the "confirmed" transformation:
> <quote>
> a more accurate definition for the Dutch system is:
> +proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889
> +k=0.999908 +x_0=155000 +y_0=463000 +ellps=bessel  +units=m
> +towgs84=565.2369,50.0087,465.658,-0.406857330322398,0.350732676542563,-1.87
> 03473836068,4.0812 
> +no_defs +to +proj=latlong +datum=WGS84
> </quote>

OK. Given these values, how would one do this using the C API, and the
pj_transform() function. Starting with WGS84 lat/long values as provided
by a GPS receiver set to provide WGS84 values?

I know that I am asking numerous similar C-API question on this list,
but I do not really feel I have it sorted out in my mind. 

Would it be:

fromProj = pj_init_plus(+proj=latlong +ellps=bessel)

toProj   = pj_init_plus(
		"+proj=sterea +lat_0=52.15616055555555 
		"+k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel
		+units=m +no_defs)

pj_transform(fromProj, toProj, 1, 0, &lng, &lat, &alt)

where lat, lng and alt are the values in radians from the GPS.

Roger Oberholtzer

OPQ Systems AB
Ramböll Sverige AB
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P.O. Box 4205
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