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
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