[Proj] Dutch correction grid
j.l.h.hartmann at uva.nl
Fri Apr 29 15:10:50 EST 2011
(About creating a grid shift file for the Dutch RD projection):
On 04/08/11 18:29, Frank Warmerdam wrote:
> 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
> 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 made a 400*400 gdal raster called dxy.tif with two bands, the first
with offsets for longitude, the second for latitude, all in arcseconds.
If I use this file in the +nadgrids clause of cs2cs, I don't see any
difference in the output. If I change the filename into something
non-existing, I don 't see any differences either and do not get an
error message. Any idea how I can test this further?
Size is 400, 400
Coordinate System is:
Origin = (3.386235000000000,50.762069400000001)
Pixel Size = (0.009627452750000,0.007066402750000)
Image Structure Metadata:
Upper Left ( 3.3862350, 50.7620694) ( 3d23'10.45"E, 50d45'43.45"N)
Lower Left ( 3.3862350, 53.5886305) ( 3d23'10.45"E, 53d35'19.07"N)
Upper Right ( 7.2372161, 50.7620694) ( 7d14'13.98"E, 50d45'43.45"N)
Lower Right ( 7.2372161, 53.5886305) ( 7d14'13.98"E, 53d35'19.07"N)
Center ( 5.3117256, 52.1753499) ( 5d18'42.21"E, 52d10'31.26"N)
Band 1 Block=400x1 Type=Float64, ColorInterp=Gray
Band 2 Block=400x1 Type=Float64, ColorInterp=Undefined
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