[gdal-dev] Why not netCDF output?

[Even Rouault]

Le lundi 27 septembre 2010 21:20:02, Joaquim Luis a écrit :
> Thanks Even,
> 
> I think that's the second time you explain me that (sorry, an easy thing
> to forget), but the docs could be a bit clearer about this. For example
> 
> *--formats*
>     List all raster formats supported by this GDAL build (read-only and
>     read-write) and exit. The format support is indicated as follows:
>     'ro' is read-only driver; 'rw' is read or write (ie. supports
>     CreateCopy); 'rw+' is read, write and update (ie. supports Create).
> 
> so I though the + was for updating

What would you suggest to be clearer ?

> 
> 
> A second point is that the command I used shows a bug in gdalwarp. In
> that the "lixo.grd" is a grid extracted from one the etopo_something
> (actually a regrid version created by me) saning [-180 180] [0 90] and
> the bug is that at dateline there is a stripe of nodata.
> Since the grid is too big to post in a ticket, can you please try to
> reproduce this?

Yes I reproduce it too. I managed to solve it by increasing the SAMPLE_STEPS 
warping option to 60 for example (input source is 5120 x 2560). See 
http://gdal.org/structGDALWarpOptions.html for more explanations

gdalwarp world.tif  -t_srs "+proj=ortho +lon_0=-42 +lat_0=40 +ellps=WGS84"  
out.tif -overwrite -wo SAMPLE_STEPS=60

> 
> Joaquim
> 
> > Joaquim,
> > 
> > The valid formats for the output of gdalwarp are formats that support the
> > Create() method, not just the CreateCopy() method. This is indicated by
> > (rw+)
> > 
> > : the + indicates that Create() is supported.
> > 
> > The difference between Create() and CreateCopy() is mainly that Create()
> > allows writing of pixel data in random order, which is needed by
> > gdalwarp.
> > 
> > You can try in 2 steps :
> > 1) gdalwarp -of VRT lixo.grd [other_options] temp.vrt
> > 2) gdal_translate -of netCDF temp.vrt proj.grd
> > 
> > Best regards,
> > 
> > Even
> > 
> >> Hi
> >> 
> >> While running this command
> >> 
> >> gdalwarp -s_srs +proj=latlong -t_srs "+proj=ortho +lon_0=-42 +lat_0=40
> >> +ellps=WGS84" -of netCDF lixo.grd proj.grd
> >> 
> >> I get
> >> 
> >> Output driver `netCDF' not recognised or does not support direct output
> >> file creation.  The following format drivers are configured
> >> (a format list where netCDF is not listed)
> >> 
> >> but if I ask gdalwarp the list of formats, netCDF is listed there as
> >> (rw). Furthermore
> >> 
> >> gdalwarp --format netCDF
> >> 
> >> Format Details:
> >>     Short Name: netCDF
> >>     Long Name: Network Common Data Format
> >>     Extension: nc
> >>     Help Topic: frmt_netcdf.html
> >>     Supports: CreateCopy() - Create dataset by copying another.
> >> 
> >> ??
> >> 
> >> Joaquim Luis
> >> 
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