[gdal-dev] convert NETCDF to Geotiff upside down

[Michael Sumner]

there is no georeferencing with this one, but as you say it has internal
coordinates (which GDAL interprets as "geolocation arrays")

so, run it through the warper i.e.

gdalwarp NETCDF:GLOBCOMPLIR_nc.2023080819:data ofn.tif

With that you can (and should) set your desired extent (-te), dimensions
(-ts) [or resolution -tr], and crs (-t_crs) but GDAL will produce an output
that works by heuristics if you specify none (or some) of those.

I did the following just for fun to see if the non-downloading pathway
would work it (not sure if the config is required or not, for testing
purposes I set dimension to 1024,0 which means GDAL figures out a sensible
aspect ratio - just remove -ts when you're happy with the result for full
resolution. )

gdalwarp --config AWS_NO_SIGN_REQUEST "YES"
NETCDF:"/vsis3/noaa-gmgsi-pds/GMGSI_LW/2023/08/08/19/GLOBCOMPLIR_nc.2023080819":data
-ts 1024 0 GLOBCOMPLIR_nc.2023080819_test.tif

(some details might not work depending on your GDAL version)

Cheers, Mike

On Thu, Aug 10, 2023 at 6:30 AM Dori <izzybitsie at gmail.com> wrote:

> Hi,
> I tried to convert the NETCDF stored in
> https://noaa-gmgsi-pds.s3.amazonaws.com/index.html#GMGSI_LW/202308/08/19/GLOBCOMPLIR_nc.2023080819
>  to Geotiff format using following command:
>
> gdal_translate 0ol GTiff -a_srs EPSG:4326 -aullr -180 -72.7 179.9 -72.7
> -co “COMPRESS=LZW” NETCDF:GLOBCOMPLIR_nc.2023080819:data ofn.tif
>
> ofn.tif is upside down.  North latitude points are in South and viceversa.
>
> How can I solve this upside down output?
> What causes this?
>
> I did notice that the points in the NETCDF file are not equidistant  what
> could be my issue.
>
> Thank you for any hint on how to go about getting the correct Geotiff
> output
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/gdal-dev
>


-- 
Michael Sumner
Software and Database Engineer
Australian Antarctic Division
Hobart, Australia
e-mail: mdsumner at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20230810/0a12f0ef/attachment.htm>