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
>>>
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>>
>>
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