Re: axis names in netcdf output files

[Joe McLean <joe.mclean@xxxxxxxx>]

Hi All,

I have been trying to help Paul off-line with an LAS issue and have not been able to come up with a solution.  Below is a snippet of e-mail from Paul oulining his needs.  Two ideas came up in a discussion with Steve Hankin.
1.  Use one of the LAS ascii ouput products and converting that to TIFF or ENVI format.
2.  There is a web service to convert netCDF to TIFF format (I don't have a URL or more details at this time).

If anyone in the las community has any other ideas, please chime in.

Thank you,
Joe

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In fact what I want to do is to get TIFF and ENVI files out of the LAS.
In order to do this, I was thinking about converting the netCDF file generated by Ferret in a TIFF or ENVI file using GDAL.
The problem I face is that Ferrret and most of image processing software do not have the image origin at the same place (UL or BL). Thus TIFF files directly generated from netCDF files produced by Ferret are up-down, like in a mirror.
My first idea was to use ncpdq from nco to reorder the latitude axis. It is working fine and very fast but I need to know the name of my latitude axis that is not anymore the name I defined in my OpenDAP server (I am using a freeform server combined with an Aggregation server).
But I can probably use the output of "ncdump -c" or "ncdump -h" in a php or perl script to identify the axis name...

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Joe McLean wrote:

> Hi Paul,
> It turns out the renaming of axes when saving data to a new NetCDF 
> file is basic Ferret behavior.  Ferret creates new axes representing 
> the sample of data which your LAS request has determined.  A namespace 
> collision would occur in Ferret if the new axis retained the name of 
> the old axis.  I think the best approach would be to use NetCDF 
> editing programs (NCO- below; ncdump, ncgen - Ferret user's guide) 
> after you have received the NetCDF file from LAS.
> Joe
>
> Joe McLean wrote:
>
> > Hi Paul,
> > Ferret automatically renames the axes based on the chosen grid 
> > sample.  My first reaction is that you would want to edit 
> > std_list.jnl to explicitly define the variable on the named axes of 
> > your choice.  I'll look into Ferret to see if this is possible and 
> > get back to you.  If you have NCO (NetCDF Operators) on your system, 
> > you can use it to rename elements of a NetCDF file after you have 
> > downloaded. http://nco.sourceforge.net/nco.html
> > Joe
> > ---------------------------
> > Paul Hasenohr wrote:
> >
> > > Dear LAS users,
> > >
> > > When a netCDF file is generated using the LAS interface, the axis 
> > > names (eg. LAT, LON) are changed in something like (LAT102_205, 
> > > LON3_304) to show what subset has been requested. This is often 
> > > convenient but for some specific purposes as an automated processing 
> > > of the netCDF files generated by the LAS product server, I would 
> > > prefer to have Ferret generating netCDF files with the original axis 
> > > names (LAT, LON in this example).
> > > Could anybody give me some hints on how to do it ?
> > > I had a look at std_list.jnl but did not find the place where this 
> > > could be modified.
> > >
> > > Thanks in advance
> > >
> > > Best regards
> > > Paul Hasenohr
> > >
> > > Paul HASENOHR
> > > European Commission - Joint Research Centre
> > > IPSC - Agriculture and Fisheries Unit
> > > TP 266, 21020 ISPRA (VA), ITALY
> > > Direct : +39 0332 78 62 22 - Fax : + 39 0 332 78 51 62
> > > Web site: http://agrifish.jrc.it
> > >
> > >