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Hi Steve, Yes, we've seen this problem before and have it on our list (https://www.unidata.ucar.edu/jira/browse/TDS-250) but somehow it hasn't floated to the top yet. We currently have it scheduled for TDS 4.4 (we're working on 4.3 currently). Ethan On 7/11/2012 12:54 PM, Steve Ansari wrote: > Hello John (and all), > > We've run into a problem using the 'As Point Dataset' time series > request with Polar Stereographic data on the TDS (version 4.2.10). For > some requests we are getting the message: > > Requested Lat/Lon Point (+80.33N 138.6W) is not contained in the Data > Data Bounding Box = lat= [30.92,90.00] lon= [-80.73,168.34] > > as seen in this request: > http://data.ncdc.noaa.gov/thredds/ncss/grid/cdr/seaice/seaice_north.ncml?var=seaice_conc_cdr&latitude=80.33203&longitude=-138.69141&temporal=range&time_start=2007-01-31T00:00:00Z&time_end=2007-12-31T00:00:00Z&vertCoord=0&accept=xml&point=true > > > The underlying issue seems to be in how the GridDataset CDM class > calculates the bounding box for this Polar Stereographic dataset. The > bounding box should be something like lat=[31, 90], lon=[-180, 180]. > Has anyone else run into problems with the Bounding Box calculations > for projected datasets? Perhaps the NetCDF-Java API is only sampling > the corners (and perhaps some points in between) of the coordinate axes > to determine the bounding box. I would think this works for the other > NetCDF-Java supported projections, but might cause issues with the > Stereographic projections. > > I'm pasting some sample code below to show that brute force reading of > each coordinate axis element value produces the correct bounding box: > > Thanks for your help! > > Steve > > > > package steve.test; > > import ucar.ma2.Array; > import ucar.nc2.dt.GridDatatype; > import ucar.nc2.dt.grid.GridDataset; > import ucar.unidata.geoloc.LatLonPoint; > import ucar.unidata.geoloc.LatLonPointImpl; > import ucar.unidata.geoloc.Projection; > import ucar.unidata.geoloc.ProjectionPoint; > import ucar.unidata.geoloc.ProjectionPointImpl; > > public class TestGridAsPointSubsetService { > > public static void main(String[] args) { > try { > String dodsURL = > "http://data.ncdc.noaa.gov/thredds/dodsC/cdr/seaice/seaice_north.ncml";; > GridDataset gds = GridDataset.open(dodsURL); > System.out.println(gds.getBoundingBox()); > > GridDatatype grid = gds.findGridDatatype("seaice_conc_cdr"); > System.out.println(grid.getCoordinateSystem().getLatLonBoundingBox()); > double minX = grid.getCoordinateSystem().getXHorizAxis().getMinValue(); > double maxX = grid.getCoordinateSystem().getXHorizAxis().getMaxValue(); > double minY = grid.getCoordinateSystem().getYHorizAxis().getMinValue(); > double maxY = grid.getCoordinateSystem().getYHorizAxis().getMaxValue(); > System.out.println("min x: "+minX); > System.out.println("max x: "+maxX); > System.out.println("min y: "+minY); > System.out.println("max y: "+maxY); > Projection proj = grid.getProjection(); > ProjectionPoint projPointLL = new ProjectionPointImpl(minX, minY); > LatLonPoint llPointLL = proj.projToLatLon(projPointLL, new > LatLonPointImpl()); > ProjectionPoint projPointUR = new ProjectionPointImpl(maxX, maxY); > LatLonPoint llPointUR = proj.projToLatLon(projPointUR, new > LatLonPointImpl()); > System.out.println(llPointLL + " , "+llPointUR); > Array xAxisData = grid.getCoordinateSystem().getXHorizAxis().read(); > Array yAxisData = grid.getCoordinateSystem().getYHorizAxis().read(); > double minLat = Double.POSITIVE_INFINITY; > double maxLat = Double.NEGATIVE_INFINITY; > double minLon = Double.POSITIVE_INFINITY; > double maxLon = Double.NEGATIVE_INFINITY; > LatLonPointImpl llp = new LatLonPointImpl(); > ProjectionPointImpl ppt = new ProjectionPointImpl(); > float[] xData = (float[])xAxisData.copyTo1DJavaArray(); > float[] yData = (float[])yAxisData.copyTo1DJavaArray(); > > for (float y : yData) { > for (float x : xData) { > ppt.setLocation(x, y); > llp = (LatLonPointImpl) proj.projToLatLon(ppt, llp); > minLat = (llp.getLatitude() < minLat) ? llp.getLatitude() : minLat; > maxLat = (llp.getLatitude() > maxLat) ? llp.getLatitude() : maxLat; > minLon = (llp.getLongitude() < minLon) ? llp.getLongitude() : minLon; > maxLon = (llp.getLongitude() > maxLon) ? llp.getLongitude() : maxLon; > } > } > // brute force range > System.out.println("brute force lat range: "+minLat+" , "+maxLat + " | > lon range: " + minLon + " , " + maxLon); > // subset service TDS URL: > // > http://data.ncdc.noaa.gov/thredds/ncss/grid/cdr/seaice/seaice_north.ncml?var=seaice_conc_cdr&latitude=80.33203&longitude=-138.69141&temporal=range&time_start=2007-01-31T00:00:00Z&time_end=2007-12-31T00:00:00Z&vertCoord=0&accept=xml&point=true > } catch (Exception e) { > e.printStackTrace(); > } > } > } > > > > _______________________________________________ > netcdf-java mailing list > netcdf-java@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ > -- Ethan Davis UCAR Unidata Program edavis@xxxxxxxxxxxxxxxx http://www.unidata.ucar.edu
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