[gdal-dev] gdal_translate precision error

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[gdal-dev] gdal_translate precision error

Marco De Nadai
Dear gdal community,
I'm a new user of gdal and I recently had a problem with precision. I tried to translate a big GeoTIFF to a smaller one, specifying the extent of the window in this way:

gdal_translate -projwin_srs EPSG:4326 -epo -strict -a_nodata 0 -projwin 9.500000 46.000000 10.000000 45.500000 -of GTiff -co COMPRESS=LZW 2015_e009_n46_e010_n45.tif try.tif

Now try.tif has extent:

8.9996489996399998,44.9992232790750890 : 10.0006417207349152,46.0002160001700062


Is this normal? Because it's a pretty big error for me.


Then, you can see this error in the map https://imgur.com/a/CNx7U. The white color is the original (source) GeoTIFF in background. The black color is try.tif and the vertical line is the extent I specified in the command.


Can you help me?

Thanks



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Marco De Nadai
Ph.D. student at Fondazione Bruno Kessler (FBK) - MobS Unit
University of Trento
Via Sommarive, 18 - Povo
38123 Trento (TN) - Italy


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Re: gdal_translate precision error

jratike80
Marco De Nadai wrote
> Dear gdal community,
> I'm a new user of gdal and I recently had a problem with precision. I
> tried
> to translate a big GeoTIFF to a smaller one, specifying the extent of the
> window in this way:

Hi,

It seems that you asked the same question in
https://gis.stackexchange.com/questions/267112/gdal-translate-numeric-accuracy-so-bad-80-meters-why
and you were asked to give more details about your source data. I consider
that it was a good suggestion.

-Jukka Rahkonen-



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Re: gdal_translate precision error

Marco De Nadai
Thanks. It seems it was a pixel-alignment error. I solved by passing coordinates aligned to pixels to gdal_translate

On Mon, Jan 8, 2018 at 3:05 PM, jratike80 <[hidden email]> wrote:
Marco De Nadai wrote
> Dear gdal community,
> I'm a new user of gdal and I recently had a problem with precision. I
> tried
> to translate a big GeoTIFF to a smaller one, specifying the extent of the
> window in this way:

Hi,

It seems that you asked the same question in
https://gis.stackexchange.com/questions/267112/gdal-translate-numeric-accuracy-so-bad-80-meters-why
and you were asked to give more details about your source data. I consider
that it was a good suggestion.

-Jukka Rahkonen-



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--
Marco De Nadai
Ph.D. student at Fondazione Bruno Kessler (FBK) - MobS Unit
University of Trento
Via Sommarive, 18 - Povo
38123 Trento (TN) - Italy


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