[Proj] OSTN02 question: GRS80 instead of Airy.

[Frank Warmerdam]

Roger Oberholtzer wrote:
> No takers on this one?
> 
> On Wed, 2006-10-25 at 12:58 +0200, Roger Oberholtzer wrote:
>> 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,

Well, you would just change +ellps=airy to +ellps=GRS80.

But perhaps your question was more subtle?

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | President OSGeo, http://osgeo.org