[Proj] OSTN02 question: GRS80 instead of Airy.

[Roger Oberholtzer]

I use the C API to do transformations. I am converting from GPS values
in WGS84 to OSTN02 for the United Kingdom. My current code is:

       fromProj = pj_init_plus(
                "+proj=latlong "
                "+ellps=WGS84 "
                "+towgs84=0,0,0 "
                "+nodefs")

        toProj   = pj_init_plus(
                "+proj=tmerc "
                "+lat_0=49 "
                "+lon_0=-2 "
                "+k=0.9996012717 "
                "+x_0=400000 "
                "+y_0=-100000 "
                "+ellps=airy "
                "+nadgrids=gb.gsb "
                "+units=m "
                "+no_defs")

Note that I do a grid shift, using data provided by a kind member of
this list.

My question is, how can I use the GRS80 ellipsoid instead of Airy? 


-- 
Roger Oberholtzer

OPQ Systems AB
Ramböll Sverige AB
Kapellgränd 7
P.O. Box 4205
SE-102 65 Stockholm, Sweden

Tel: Int +46 8-615 60 20
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