I am fairly certain that the y-flip issue is fixed in gdal, and it also
handles all of the grid_mapping values/projections in cf-1.4. Arc uses
GDAL-1.6 right now, but I believe that they will make the jump to 1.8.x
where these issues have been implemented.
# ============================
Kyle Shannon
Physical Science Technician
RMRS Fire Sciences Lab
Fire, Fuels & Smoke - RWU 4405
5775 Highway 10 W.
Missoula, MT 59808
(406)829-6954
kshannon@xxxxxxxxx
# ============================
On Tue, Mar 22, 2011 at 08:29, Roy Mendelssohn <Roy.Mendelssohn@xxxxxxxx>wrote:
> ArcGIS and Mapserver both make heavy use of GDAL, and the fact that they
> work together is probably more a reflection of the shared code base than
> that they necessarily do something correctly. While GDAL is a great
> library, I have had similar problems in how it handles OPeNDAP and netCDF
> files (it flips the images), in cases where the grids etc were clearly
> specified in CF conventions - they were just being ignored and GDAL was
> imposing its own interpretations.
>
> The question is not whether ArcGIS works with MapServer, but whether the
> WCS service implemented in THREDDS correctly follows the standard, and
> provides enough information for a client to interpret what it receives
> correctly. If the answer is yes, then we should be talking to ESRI et al.
> about implementing their client correctly to follow the standard. The
> equivalent would be saying I should change my CF compliant netCDF files to
> suit GDAL, rather than have GDAL learn the standard.
>
> My $0.02.
>
> -Roy
>
> On Mar 21, 2011, at 3:21 PM, David Neufeld wrote:
>
> > Hi Ethan, Jay,
> >
> > Below are my notes about problems with THREDDS WCS and ArcGIS when I last
> looked at the issue (about 6 mos ago). I'm not sure if there have been any
> recent changes in THREDDS or ArcGIS that may have addressed the problem yet.
> The link to a PDF at the bottom includes some screen snap shots from ESRI's
> ArcCatalog and ArcMap.
> >
> > -Dave
> >
> >
> >
> >
> >
> >
> >
> >
> > -------- Original Message --------
> > ArcMap is not correctly displaying coverages from a THREDDS WCS. The
> > problem appears to be with differences in the DescribeCoverage response
> > in THREDDS compared to MapServer (ArcMap does display WCS coverages from
> > UMN MapServer). Specifically the problem appears to be related to the
> > way the origin and offset vector are reported.
> >
> > ArcMap appears to expect the origin of the Grid to be described in terms
> > of its upperleft corner with the offset vector described accordingly.
> >
> > This is a DescribeCoverage response coming from MapServer (note origin
> > is upperleft corner; offset vector for y is negative):
> >
> > <gml:RectifiedGrid dimension="2">
> > <gml:limits>
> > <gml:GridEnvelope>
> > <gml:low>0 0</gml:low>
> > <gml:high>21600 10800</gml:high>
> > </gml:GridEnvelope>
> > </gml:limits>
> > <gml:axisName>x</gml:axisName>
> > <gml:axisName>y</gml:axisName>
> > <gml:origin>
> > <gml:pos>-180.008333333335 90.008333369335</gml:pos>
> > </gml:origin>
> > <gml:offsetVector>0.01666666667 0</gml:offsetVector>
> > <gml:offsetVector>0 -0.01666666667</gml:offsetVector>
> > </gml:RectifiedGrid>
> >
> > Currently the DescribeCoverage response from THREDDS contains the
> > following for the gml:RectifiedGrid (note origin is lowerleft corner;
> > offset vector for y is positive).
> >
> > <gml:RectifiedGrid srsName="OGC:CRS84" dimension="2">
> > <gml:limits>
> > <gml:GridEnvelope>
> > <gml:low>0 0</gml:low>
> > <gml:high>21600 10800</gml:high>
> > </gml:GridEnvelope>
> > </gml:limits>
> > <gml:axisName>x</gml:axisName>
> > <gml:axisName>y</gml:axisName>
> > <gml:origin>
> > <gml:pos>-180.0 -90.0</gml:pos>
> > </gml:origin>
> > <gml:offsetVector>0.016666666666666666 0.0</gml:offsetVector>
> > <gml:offsetVector>0.0 0.016666666666666666</gml:offsetVector>
> > </gml:RectifiedGrid>
> > </spatialDomain>
> >
> > This appears to cause ArcMap to formulate the following GetCoverage
> > request to THREDDS after parsing the DescribeCoverage response (as noted
> > by Kevin Sampson):
> >
> > 127.0.0.1 - - [12/Oct/2010:14:53:53 -0600] "GET
> >
> /thredds/wcs/test/ETOPO1_Ice_g_gmt4.nc?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&COVERAGE=z&FORMAT=GeoTIFF&BBOX=-180.008333333333,-89.975,-179.975,-90.0083333333333&WIDTH=2&HEIGHT=2&CRS=&INTERPOLATION=nearest%20neighbor
> > HTTP/1.1" 400 331
> >
> > At which point THREDDS reports an exception:
> >
> > <?xml version="1.0" encoding="UTF-8"?>
> > <ServiceExceptionReport xmlns=
> > "http://www.opengis.net/ogc";
> > version="1.2.0">
> > <ServiceException code="InvalidParameterValue" locator="BBOX">BBOX
> > [-180.008333333333,-89.975,-179.975,-90.0083333333333] minimum point
> > larger than maximum point.</ServiceException>
> > </ServiceExceptionReport>
> >
> >
> > Full report is available here:
> >
> >
> https://sites.google.com/site/geointeropdemos/home/issues-with-thredds-wcs/WCS_Comments_NGDC_v1.1.pdf
> > _______________________________________________
> > thredds mailing list
> > thredds@xxxxxxxxxxxxxxxx
> > For list information or to unsubscribe, visit:
> http://www.unidata.ucar.edu/mailing_lists/
>
> **********************
> "The contents of this message do not reflect any position of the U.S.
> Government or NOAA."
> **********************
> Roy Mendelssohn
> Supervisory Operations Research Analyst
> NOAA/NMFS
> Environmental Research Division
> Southwest Fisheries Science Center
> 1352 Lighthouse Avenue
> Pacific Grove, CA 93950-2097
>
> e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
> voice: (831)-648-9029
> fax: (831)-648-8440
> www: http://www.pfeg.noaa.gov/
>
> "Old age and treachery will overcome youth and skill."
> "From those who have been given much, much will be expected"
>
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