Hi Kyle, I made now the time-dimension 2-dimensional, i.e. time(obs, trajectory), removing the one simplification made below. netcdf-java seems now to be able to read the trajectories. Since the page: http://www.unidata.ucar.edu/software/thredds/current/netcdf-java/reference/FeatureDatasets/CFpointImplement.html already mentions differences from CF, maybe this one could be entered there, too? (Or maybe it's easy to extend the cdm to support one-dimensional time-axes?) I wasn't able to plot trajectories as seen in netcdf-java 2.2. Is it just me not finding the right buttons or was this feature removed? This is not critical, but would be nice for debugging. But the most important point is that we now know how to create a netcdf-java compliant trajectory file. Thanks for your help. Heiko On 2015-08-27 20:17, Heiko Klein wrote: > Hi Kyle, > > we're trying to use quite strictly H.4.1 here, with one addition: > > Since all trajectories have the same timesteps we use 'time'='obs' and > we don't have a special obs dimension. According to CF, this is allowed: > (Chapter H.4.1: "If the trajectories all have the same set of times, the > time auxiliary coordinate variable could be one-dimensional time(obs), > or replaced by a one-dimensional coordinate variable time(time), where > the size of the time dimension is now equal to the number of elements of > each trajectory. In the latter case, listing the time coordinate > variable in the coordinates attribute is optional.") > > Best regards, > > Heiko > > > On 2015-08-27 16:22, Kyle Wilcox wrote: >> Hi Heiko, >> >> At first glace, I can't figure out which CF specification you were >> trying to adhere to: H.4.1, H.4.2, H.4.3, or H.4.4. It appears you may >> have tried to adopt H.4.2 to use multiple trajectories, which I'm not >> sure is supported in NetCDF-Java. >> >> Take a look at these Trajectory >> examples: >> https://github.com/asascience-open/CFPointConventions/tree/master/trajectory. >> Each folder contains a .cdl, .nc (that will load into NetCDF-Java), and >> an .ncml file. >> >> Hope that helps, >> Kyle >> >> >> On Thu, Aug 27, 2015 at 4:21 AM, Heiko Klein <Heiko.Klein@xxxxxx >> <mailto:Heiko.Klein@xxxxxx>> wrote: >> >> Hi, >> >> I'm trying to read trajectory data with netcdf-java. I've seen figures >> of this with netcdf-java 2.2 at >> >> >> https://www.unidata.ucar.edu/software/thredds/v4.3/netcdf-java/tutorial/PointDatatype.html >> >> but both netcdf-4.6 and CF-1.6 have a different layout for >> trajectory data. >> >> >> >> I've tried now to generate a netcdf/CF file following the guidelines at >> >> http://www.unidata.ucar.edu/software/thredds/current/netcdf-java/reference/FeatureDatasets/CFpointImplement.html >> (see attached file). >> >> >> ToolsUI gives me a 'CoordSys' with trajectory, time, lat, lon and >> time,lat,lon have the expected axisTypes. Using FeatureScan, I get a >> coverage of 'Swath(T,Y,X): trajectory', which looks ok, but I get also >> an error message: >> >> --------- >> /home/heikok/openoil2.nc4 >> NetCDF-4 >> map = 'f:D(2)->R(4)' >> >> null >> >> CoverageFactory for '/home/heikok/openoil2.nc4' >> coverage = Swath >> FeatureDatasetFactoryManager errlog = Table >> PsuedoStructure(trajectory)/MultidimPseudo(trajectory,time) featureType >> TRAJECTORY: lat/lon/time coord not found >> **Failed to find FeatureDatasetFactory for= /home/heikok/openoil2.nc4 >> datatype=TRAJECTORY >> ---------- >> >> >> According to 'CoordSys', lat/lon/time are availble. >> >> The PointFeature/TRAJECTORY wasn't then able to plot the data. Any idea >> how I can correct my data to enable plotting in netcdf-java UI? >> >> >> Best regards, >> >> Heiko >> >> >> >> _______________________________________________ >> netcdf-java mailing list >> netcdf-java@xxxxxxxxxxxxxxxx <mailto:netcdf-java@xxxxxxxxxxxxxxxx> >> For list information or to unsubscribe, visit: >> http://www.unidata.ucar.edu/mailing_lists/ >> >> >
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