Re: [thredds] future TDS WCS support for irregular/curvilinear grids?

Can you use JPEG from WMS ? Is there something more that you use from GeoTiff?

Very cool map app, is that built eith Google Maps, or are you just emulating the interface?


On 6/15/2011 11:28 PM, John Maurer wrote:
Hi John,
Thanks for this clarification. I'm referring to curvilinear grids (2d) in our case at the moment. And yep, again, this would be for GeoTIFFs; for those geospatial folks (mostly in the GIS community) for whom a NetCDF is undesirable. Here's an example map from our Google Maps-based viewer that pulls a tiled image overlay directly from TDS using ncWMS (wave height forecast over Oahu). If you click on the map, it provides a GeoTIFF URL. I limit the GeoTIFF link to our regular gridded datasets, but was hoping to (someday) expand this to the rest of our forecast models (curvilinear):

http://www.soest.hawaii.edu/hioos/map/index.html?b=21.042210,-158.815613,21.906100,-157.134705&t=h&o=bath:2:75:0,sfore:1:ft:d5m0.x5.524t1308196800 <http://www.soest.hawaii.edu/hioos/map/index.html?b=21.042210,-158.815613,21.906100,-157.134705&t=h&o=bath:2:75:0,sfore:1:ft:d5m0.x5.524t1308196800>

Thanks for listening,
John Maurer
Pacific Islands Ocean Observing System (PacIOOS)
University of Hawaii at Manoa

On Wed, Jun 15, 2011 at 5:00 PM, john caron <caron@xxxxxxxxxxxxxxxx <mailto:caron@xxxxxxxxxxxxxxxx>> wrote:

    some terms as far as i understand:

    regular grids:                    1d x, y coordinates evenly
    spaced. only ones WCS 1.0 allows
    irregularly spaced grids:  1d x,y, but dont have to be even, eg
    gaussian latitudes.
    curvilinear grids:                2d x,y but each section is a
    quadilateral and connected to its neighbor (implicit topology)

    CF allows both irregular and curvilinear grids. one could extend
    WCS to return netcdf/CF irregular and curvilinear grids, without
    regridding.

    unstructured grids: arbitrary meshes, explicit topology, no CF
    standard yet.

    John, why do you want WCS? To get geotiffs, or ??

    On 6/15/2011 7:25 PM, Ben Domenico 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
    <mailto: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 <mailto: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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