[gdal-dev] kml to wld

[Daniele Romagnoli]

Hi Luca,
actually, the coefficients of a world file aren't simply pixel size and
rotation. Therefore, with a rotation in the mix, you may need to do some
math :(
You may want to take a look a the world file definitions to see what these
6 coeffs represent:
https://en.wikipedia.org/wiki/World_file

I never had to deal with such cases so I can't provide you additional
information.
However, looks like someone else already faced that problem:
https://gis.stackexchange.com/questions/12181/how-to-generate-a-world-file-with-rotation

Hope this provides you some hint to solve the problem.
Regards,
Daniele





On Tue, Oct 2, 2018 at 1:37 PM Luca Delucchi <lucadeluge at gmail.com> wrote:

> Hi all,
>
> I need to use the coordinates information contained in a kml file to
> write a wld file.
>
> In the KML I have
>
> <LatLonBox>
>     <north>47.551729</north>
>     <south>45.438335</south>
>     <east>12.736706</east>
>     <west>9.670600</west>
>     <rotation>-1.35</rotation>
> </LatLonBox>
>
> I converted them to UTM WGS84 32N coordinate system
>
> <LatLonBox>
>     <north>5273247.79</north>
>     <south>5031864.43</south>
>     <east>781130.01</east>
>     <west>552448.98</west>
>     <rotation>-1.35</rotation>
> </LatLonBox>
>
> I calculated the resolution doing the differences between north/south
> and east/west and I get 251.441 and 238. To have squared pixel I would
> set to 250 (maybe it could be better to use 240?).
>
> with this info I created the wld file
>
> 250
> -1.35
> -1.35
> 250
> 552448.98
> 5273247.79
>
> The reprojection works quite well, but it seems shifted by some
> pixels, does the procedure make sense or is completely wrong?
>
> PS
> With latlong values the image is located in a wrong place, but the wld
> seems correct, maybe the pixel value is wrong.
>
> 0.002201452083
> -1.35
> -1.35
> -0.002201452083
> 9.670600
> 47.551729
>
>
> --
> ciao
> Luca
>
> www.lucadelu.org
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/gdal-dev



-- 
Regards,
Daniele Romagnoli
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