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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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> Does WMS/WCS allow other than lat/lon bounding boz? Yes, you can specify a BBOX in other coordinate systems *as well* as a lat-lon BBOX. Therefore we need an accurate (even if it isn't precise) BBOX in lat-lon. If in doubt, a BBOX that covers the whole world is at least valid, even if it's not terribly helpful. (the lat-lon BBOX is really a hint to search and visualization systems.) > LLbb= ll: 34.57N 79.65W+ ur: 90.0N 169.6E Yes, this is definitely an improvement over what I get from version 2.2.22 but still not right - it should cover the whole longitude range (the latitude range looks reasonable though.) Thanks for your help, Jon On Jan 26, 2008 7:37 PM, John Caron <caron@xxxxxxxxxxxxxxxx> wrote: > Yes, i can imagine that a polar projection will give bad results for the > lat/lon BB. We really need to replace that with a bounding polyline. Does > WMS/WCS allow other than lat/lon bounding boz? > > I did check the dataset pointed to by ArcticTEP.ncml, and it had a reasonable > bounding box: > > LLbb= ll: 34.57N 79.65W+ ur: 90.0N 169.6E > > still not great, but not empty at least. I see that you're using TDS 3.14, im > not sure if ive fixed a bug (im testing with 4.0.11 alpha) or we are looking > at different datasets.... Ill make a release on monday so that you can check > against 4.0, and i'll look at your specific dataset next week. > > > Jon Blower wrote: > > Hi John, > > > > That's brilliant, thanks very much. Everything (nearly) now appears to > > work: > > > > http://lovejoy.nerc-essc.ac.uk:8080/ncWMS/mersea.html?menu=MERSEA&layer=MERSEA_ARCTIC_TOPAZ/temperature&elevation=-5&time=2008-01-24T00:00:00Z&scale=-3.055269694328308,22.592125034332277&bbox=-65.039062,18.28125,24.960938,88.59375 > > > > However, there seems to be a problem with > > GridCoordSystem.getLatLonBoundingBox() for this dataset (presumably > > because of the polar stereographic projection). This function returns > > a zero-sized bounding box (with minLat = maxLat). The longitude range > > also appears wrong. I would expect this to return a BBOX of the form > > (-180, minLat, 180, 90), i.e. covering the full longitude range and > > ranging from some minimum latitude to the North Pole. > > > > The ncml file is attached that contains your metadata corrections, in > > case you want to test getLatLonBoundingBox(). > > > > Cheers, Jon > > > > On Jan 22, 2008 12:25 AM, John Caron <caron@xxxxxxxxxxxxxxxx> wrote: > >> Hi Jon: > >> > >> 1) y coordinate is missing units attribute > >> 2) latitude unit should be "degrees_north", not "degrees" > >> 3) longitude unit should be "degrees_east", not "degrees" > >> 4) most of the the data variables have "_CoordinateAxes" attributes > >> missing the time coordinate, eg: > >> > >> :_CoordinateAxes = "longitude latitude y x "; > >> > >> should be: > >> > >> :_CoordinateAxes = "longitude latitude y x time "; > >> > >> The rule for "_CoordinateAxes" is that they have to be complete, if you > >> are going to use them. If > >> you left "_CoordinateAxes" off, then the CF-1.0 convention > >> > >> :coordinates = "longitude latitude"; > >> > >> would work, since the coordinate variables (x,y,time) would be > >> automatically added. > >> > >> Jon Blower wrote: > >>> Hi all, > >>> > >>> I'm trying to use the Java NetCDF libraries (2.2.22) to read Arctic > >>> ocean data over OPeNDAP. The data are in polar stereographic > >>> projection. However, the following short program (which works fine > >>> for many other datasets) returns zero Grids: > >>> > >>> NetcdfDataset nc = NetcdfDataset.openDataset(url, true, null); > >>> GridDataset gd = > >>> (GridDataset)TypedDatasetFactory.open(DataType.GRID, nc, null, null); > >>> System.out.println(gd.getGrids().size()); // prints out "0" > >>> > >>> The URL to the OPeNDAP site is > >>> http://topaz.nersc.no/thredds/dodsC/topaz/mersea-ipv2/arctic/tmipv2a-class1-be. > >>> The results of performing an ncdump on this URL (using toolsUI) are > >>> attached. toolsUI also fails to recognize any Grids in this dataset. > >>> > >>> Can anyone advise on what might be the problem here? Is the metadata > >>> of the dataset incorrectly specified? > >>> > >>> Thanks in advance, > >>> Jon > >>> > >>> > >>> > >>> ------------------------------------------------------------------------ > >>> > >>> _______________________________________________ > >>> netcdf-java mailing list > >>> netcdf-java@xxxxxxxxxxxxxxxx > >>> For list information or to unsubscribe, visit: > >>> http://www.unidata.ucar.edu/mailing_lists/ > > > > > > > -- -------------------------------------------------------------- Dr Jon Blower Tel: +44 118 378 5213 (direct line) Technical Director Tel: +44 118 378 8741 (ESSC) Reading e-Science Centre Fax: +44 118 378 6413 ESSC Email: jdb@xxxxxxxxxxxxxxxxxxxx University of Reading 3 Earley Gate Reading RG6 6AL, UK --------------------------------------------------------------
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