[Proj] Dutch correction grid

Frank Warmerdam warmerdam at pobox.com
Fri Apr 8 11:29:53 EST 2011

On 11-04-08 11:28 AM, Jan Hartmann wrote:
> I don't quite understand, Frank. I have a spreadsheet with four columns: x, y,
> correction for x and correction for y. What kind of raster file do I need to
> create with these data?


As input we would require an input raster with two "bands" representing the
offset in longitude and latitude.   I'm not sure off hand what the units
are - possibly arcseconds?   The input file would need to be georeferenced
in latitude and longitude.

If your input points are sparse and irregular you could likely use
gdal_grid to interpolate a grid from the point data.

My point was mainly that you don't necessarily have to write an NTv2
"writer" - it is sufficient to get the datum shift data into any GDAL
support grid format.

Best regards,

I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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