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I am using GDAL library in C++. On my dataset, I have obtained geo transform with GetGeoTransform to GT array (GCP is NULL).

Than I use this values for this equation (Source):

Xgeo = GT(0) + Xpixel*GT(1) + Yline*GT(2)
Ygeo = GT(3) + Xpixel*GT(4) + Yline*GT(5)

I also add 0.5 offset to Xpixel and Yline, to calculate coordinate in the "center" of pixel.

If I put [0,0], I got correct result in lat/lon. However, if I change Yline to something other than 0, my longitude is messed up - instead of 44.0, I got -349.2... (latitude is still correct). What am I doing wrong ?

My data informations - origin, pixel size and top left are taken from GT array used in equation above; projection is GetProjectionRef

Projection is `GEOGCS["Coordinate System imported from GRIB file",DATUM["unknown",SPHEROID["Sphere",6371200,0]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]'
Origin = (0,0) - GT(2), GT(4)
Pixel Size = (0.5,-33.268) - GT(1), GT(5)
Top Left = (5.75,66.634) - GT(0), GT(3)
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  • Add bebug of all value and type passed in tour formulas.thanks
    – GeoStoneMarten
    Commented Nov 28, 2015 at 9:18

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You should correct the size of your pixel in Y. -33 degree is definitely too much.

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  • That is, what I get from GDAL on opened data. I am not editing those values.
    – Martin Perry
    Commented Dec 23, 2013 at 12:15

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