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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" > > _______________________________________________ > thredds mailing list > thredds@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ >
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