[gdal-dev] gdal_translate a VRT built on top of GeoTIFFs with NaN

Daniele Romagnoli daniele.romagnoli at geo-solutions.it
Mon May 2 05:52:41 PDT 2016


Hi Even.
Thanks for the feedback.

Sorry... I'm using GDAL 1.11.3.
I'm going to double check to make sure I didn't make any mistake.
I'll let you know.

Cheers,
Daniele



On Mon, May 2, 2016 at 2:49 PM, Even Rouault <even.rouault at spatialys.com>
wrote:

> Le lundi 02 mai 2016 14:37:39, Daniele Romagnoli a écrit :
> > Hi List,
> >
> > I have a reprojectiion tool which creates GeoTIFFs with NoData = NaN.
> > I'm creating couple of GeoTIFFs with partially overlapping areas where
> > GeoTIFF1 has NaNs in a region and GeoTIFF2 has proper values in the same
> > overlapping region and viceversa (GeoTIFF2 has some NaN area while
> GeoTIFF1
> > has valid pixels for same area).
> > I have built a VRT on top of them and then translated into a single
> > GeoTIFF. However, the result has NaN in those regions.
> > I was hoping that the area containing NaNs would have been ignored
> instead,
> > in favor of proper values from the other file.
> > Is there any flag, properties or suggestions to make it working?
> >
> > If I configure the reprojection tool to write NoData = -9999 and then use
> > gdalbuildvrt -srcnodata -9999, things are working fine.
> > So I'm just wondering if the same can be achieved dealing with NaN
> instead
> > of custom values.
>
> Daniele,
>
> You didn't mention which GDAL version you use. It is possible that support
> for
> NaN as a nodata value in gdalbuildvrt & the VRT driver was fixed at some
> point.
> From a quick test with trunk, it works  (works with 1.11 branch as well):
>
> $ cat in1.asc
> ncols        3
> nrows        3
> xllcorner    440720.000000000000
> yllcorner    3750120.000000000000
> cellsize     60.000000000000
> NODATA_value    nan
>  1.0 1.0 1.0
>  1.0 nan 1.0
>  1.0 1.0 1.0
>
> $ cat in2.asc
> ncols        3
> nrows        3
> xllcorner    440720.000000000000
> yllcorner    3750120.000000000000
> cellsize     60.000000000000
> NODATA_value    nan
>  nan nan nan
>  nan 2.0 nan
>  nan nan nan
>
> $ gdalbuildvrt nan.vrt in1.asc in2.asc
>
> $ gdal_translate nan.vrt /vsistdout/ -of aaigrid
> ncols        3
> nrows        3
> xllcorner    440720.000000000000
> yllcorner    3750120.000000000000
> cellsize     60.000000000000
> NODATA_value    nan
>       1      1      1
>       1      2      1
>       1      1      1
>
>
> Even
>
> --
> Spatialys - Geospatial professional services
> http://www.spatialys.com
>



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