Hi Steve,
So the OGC community has (at least so far) decided that explicit translations between coordinate reference systems do not belong inside of their data representations.
This doesn't surprise me. GIS systems should be able to convert between different coordinate reference systems. I would not worry about reading netCDF files containing lat/lon coordinates into a GIS package. I was more thinking of all the other tools that are used. For instance MATLAB won't do automatic on the fly conversion between coordinate reference systems. Although, with MATLAB you can either use The MathWorks' or Rich Pawlowicz's mapping toolbox to do the conversion manually once you have figured out what the appropriate transformations are. Several other visualisation program's, however, are neither GIS product nor are they as programmable as MATLAB. For such programs it would be good to have the appropriate coordinate data already in the file.
CF has already gone one step beyond this (and adds value in doing so). But I believe that keeping CF "lean and mean" will pay off over the long term, so we should carefully consider alternative solutions outside of CF before adding further complexity to the standard. (Sorry if I'm sledge hammering this point.)
I agree, lean and mean is best in general.
[some TDS and NcML information]
Okay, all immutable data is stored only once. Separate grid files for local coordinates. Local TDS server required to combine the files based on NcML XML file. I will investigate this line further, but that will take some time.
If it is local files that your community really needs, and the service-oriented aspects of TDS do not add any value, then (as you have said) you don't need OPeNDAP. In fact, there is plenty of richness in the netCDF utilities that already exist (e.g. nco), so that you can create German and Dutch flavors of your files using nothing but simple scripts to do the same things that are described from TDS above. No changes to CF are required. And it would not be a particularly messy data management task.
Thanks for the information. I will have a look at the NCO tools.
In the footnote I was assuming that the theoretical discussion was of grid objects that described both horizontal and vertical and files that mixed 2D and 3D spatial grids. There are plenty of subtleties in the vertical, too, particularly for hybrid coordinate models. Sorry for opening up this distracting point.
I agree that grids in the vertical direction are far from trivial. It seems that keeping horizontal and vertical coordinates separated as much as possible (maybe have anisotropic grid objects).
Thanks for your patience with this process - Steve
Thank you for your comments and ideas.
Best regards,
Bert
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Received on Thu Dec 07 2006 - 02:00:07 GMT
