Hi Jon, Thanks for the follow-up. It would be great (in my opinion) to get this nearest-neighbour scheme folded into the TDS WCS for GeoTIFF output. I was hoping something like that could be possible with some (hopefully relatively painless?) re-use of your code. I also completely concur with your aside about GIS users. Cheers John ncWMS (and hence THREDDS-WMS) uses a simple nearest-neighbour scheme for > regridding, which seems fine for producing images (at least, no-one has ever > complained!) but may not be appropriate for serving data, depending on what > you want to do.**** > > ** ** > > However, if THREDDS wants a means to serve resampled data through WCS, the > WMS libraries should make this pretty easy to implement. But the user must > be aware that the data have been processed at the server side.***** > > ** ** > > We would also need to implement GeoTIFF output for your needs… probably > there is code out there to do this already.**** > > ** ** > > Hope this helps,**** > > Jon**** > > ** ** > > [* Aside: in my view, the WCS interface is most useful for GIS users, who > are much less likely to care about how data are regridded than scientific > users; scientific users can use OPeNDAP to get the “raw” data of course. > Perhaps in most cases, GIS users just need a “WMS for data” rather than a > full-fledged scientific data server. But I don’t know how THREDDS-WCS is > used in the wild.]**** > > ** ** > > ** ** > > *From:* John Maurer [mailto:jmaurer@xxxxxxxxxx] > *Sent:* 16 June 2011 02:47 > *To:* THREDDS Users > *Cc:* Jon Blower > > *Subject:* Re: [thredds] future TDS WCS support for irregular/curvilinear > grids?**** > > ** ** > > Thanks, Ben! Sounds good! Glad to hear things are progressing along these > lines. Sounds like it could be quite some time, though, before irregular > grids are formally adopted by the international standards community and > trickle down to all of us here in TDS-land. This is why I was hoping Unidata > could maybe short circuit this process by regridding the data onto a regular > grid via the TDS backend and then serving it out through WCS (1.0) that way. > But that is maybe asking (way) too much. Again, ncWMS is presumably doing > something similar to provide WMS for irregular grids (see attached image)? > Or is the WMS spec ahead of WCS in terms of its adoption of irregular grids? > Perhaps Jon Blower could elucidate (cc'd)... > > > [image: sst_roms_curvilinear.png] > > Cheers, > John Maurer**** > > On Wed, Jun 15, 2011 at 3:25 PM, Ben Domenico <Ben@xxxxxxxxxxxxxxxx> > wrote:**** > > Hi John et al.,**** > > ** ** > > I am currently at the OGC Technical Committee meetings so your note is > quite timely. My concept of how this sort of capability might be worked > into the standards -- from the netCDF point of view anyway -- is via the CF > conventions. We are currently working on a CF extension for the OGC > netCDF core standard. At the same time we are working on a CF-netCDF > encoding standard for WCS 2.0. But my understanding is that > irregular/curvilinear grids are not formally adopted yet as part of the CF > conventions. When these grids officially become part of CF, we can then do > a revised extension to CF-netCDF and to WCS.**** > > ** ** > > Please correct me if I'm wrong about the status of irregular/curvilinear > grids in CF. If you have suggestions for better ways to accomplish this, > let me know. But for now this is the general outline of the plan for > getting this into the formal standards world. **** > > ** ** > > For what it's worth.**** > > -- Ben**** > > ** ** > > On Wed, Jun 15, 2011 at 6:23 PM, John Maurer <jmaurer@xxxxxxxxxx> wrote:** > ** > > Thanks for the explanation, Ethan. If TDS could handle the regridding > itself, then it could work. I assume this is what's happening on the backend > via TDS/ncWMS for GetMap requests since the WMS spec doesn't handle > irregular/curvilinear grids either (right?). I was hoping a future > enhancement could someday do the same for TDS WCS. Something for the > suggestion box. > Cheers, > John**** > > ** ** > > On Wed, Jun 15, 2011 at 2:17 PM, Ethan Davis <edavis@xxxxxxxxxxxxxxxx> > wrote:**** > > Hi John, > > TDS currently only supports WCS 1.0.0. The WCS 1.0.0 specification > itself does not support requesting or returning irregular/curvilinear > grids. I believe the same is true for WCS 1.1.0. > > I don't belive this is necessarily the case for WCS 2.0. However, the > 2.0 specification is written in the new core/extensions paradigm and I > don't believe the extensions necessary to request or return > irregular/curvilinear grids are yet written. > > The TDS WCS implementation does not currently support regridding data. > So, currently one gets the data from the WCS in the same projection in > which the data is stored. The combination means the TDS WCS can only > serve regularly gridded data. > > Ethan**** > > > On 6/15/2011 5:31 PM, John Maurer wrote: > > Hi All, > > We now use the WCS service through TDS to serve GeoTIFF files to users. > > Since it only works for regular grids, I was wondering if TDS could be > > enhanced in the future to support irregular/curvilinear grids via WCS? > > TDS/ncWMS already handles curvilinear grids via WMS, so I was hoping the > > same sort of intervening magic could be applied for TDS' WCS service? > > Thoughts? > > Thanks for listening!, > > John Maurer > > Pacific Islands Ocean Observing System (PacIOOS) > > University of Hawaii at Manoa**** > > _______________________________________________ > thredds mailing list > thredds@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/**** > > ** ** > > > _______________________________________________ > thredds mailing list > thredds@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ **** > > ** ** > > ** ** >
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