[gdal-dev] Question on converting netCDF to GTiff

[Stephen Woodbridge]

On 10/23/2019 1:54 PM, Even Rouault wrote:
> On mercredi 23 octobre 2019 13:41:45 CEST Stephen Woodbridge wrote:
>> Hi,
>>
>> I have a netCDF grid of Float32 values that I want to convert to GTiff
>> with Int16 values. The min/max values will support this without scaling,
>> but I'm not sure what will happen to the NODATA value =
>> 9.96920996838686905e+36.
>>
>> Ideally, I would like to set it to something like 32000 but not sure how
>> to do that.
>>
>> I've gotten as far as:
>>
>> gdal_translate -of GTiff -co TILED=YES -ot Int16 -a_srs EPSG:4326
>> GEBCO_2019.nc  gebco_2019.tif
>>
>> Which runs and looks ok except NODATA is set the same and that value
>> clearly will not fit in an Int16. Now it is possible that the grid
>> doesn't actually have any nodata cells set and only has the value
>> defined but I'm not sure how to check if that is the case.
> To check if there are cells set to NODATA, with recent enough GDAL (3.0 I
> think), with gdalinfo -stats, you'll see a STATISTICS_VALID_PERCENT item. If
> it is not 100, then there are nodata cells.
>
> To do nodata value remapping, use gdalwarp -srcnodata XX -dstnodata YY
>
> Even
>
Thanks gdalwarp does the job nicely.

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