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
>
>
>
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>
--
Dr. Heiko Klein Norwegian Meteorological Institute
Tel. + 47 22 96 32 58 P.O. Box 43 Blindern
http://www.met.no 0313 Oslo NORWAY
