Hi Niels, Nuno fixed a bug in the NetCDF machinery a couple of days ago. (I have merged that PR right now). At the very beginning of the NetCDF development, we started to support what was able with the available NetCDF version (I thin 2.x or something similar... a very old one). Therefore the NetCDF reader also internally deal with a binary index containing Time,Zeta based indexes for quick slices retrieval.
https://github.com/geotools/geotools/blob/master/modules/plugin/coverage-multidim/netcdf/src/main/java/org/geotools/imageio/netcdf/Slice2DIndex.java Basically, re-using the table I have put in the JIRA, for each 2D pair a global index may be defined: global Index =(Time index, Zeta Index) 0 = (0,0) 1 = (0,1) 2 = (0,2) 3 = (1,0) 4 = (1,1) 5 = (1,2) 6 = (2,0) 7 = (2,1) 8 = (2,2) 9 = (3,0) 10= (3,1) 11= (3,2) The NetCDF internal catalog is similar to the ImageMosaic GranuleCatalog. For each 2D slice available, it stores a global index, as well as the timestamp/date (it T dimension is available) and the elevation value (it Z dimension is available) related to that imageIndex. ( https://github.com/geotools/geotools/blob/master/modules/plugin/coverage-multidim/coverage-api/src/main/java/org/geotools/coverage/io/catalog/CoverageSlicesCatalog.java ) So, when requesting a read operation on a specific time and specific elevation, the reader performs a query on the CoverageSlicesCatalog to get the related imageIndex. Then the imageIndex is provided to the Slice2DIndexManager in order to get the proper integer indexes to be used as values for the Section/Ranges to be provided to the underlying UCAR reader. https://github.com/geotools/geotools/blob/master/modules/plugin/coverage-multidim/netcdf/src/main/java/org/geotools/imageio/netcdf/NetCDFImageReader.java#L584 https://github.com/geotools/geotools/blob/master/modules/plugin/coverage-multidim/netcdf/src/main/java/org/geotools/imageio/netcdf/NetCDFImageReader.java#L651-L658 We also thought about revisiting/removing the binary index machinery and include it somehow this information in the CoverageSlicesCatalog itself and investigate on the indexing objects automatically generated by the UCAR library. However we never had time or resources to work on that. Therefore, right now, an additional real dimension for runtime isn't fully supported. (We somehow support different runtimes for different NetCDF through ImageMosaic store). Not sure to remember from which version UCAR started exposing it as a separate dimension. You may want to extend the Slice2DIndex machinery or remove that in favor of a better management of additional dimensions. Does it helps? Cheers, Daniele On Fri, Sep 23, 2016 at 2:34 PM, Niels Charlier <ni...@scitus.be> wrote: > Hello Daniele, > > As you know, I am working on support for aggregation on runtime dimension > in netcdf. I am now looking into what needs to happen in VariableAdaptor. > I am very new at netcdf, so I do not yet understand everything that is > happening to the fullest extent in this class. > > I have found a way to make it work, basically by ignoring the runtime > dimension altogether. Apart from adding it as an ignored dimension, I also > had to take into account the possibility of there being four dimensions of > which one is the runtime dimension. > > This is the commit: https://github.com/NielsCharli > er/geotools/commit/5278115bd43a77c6509881d59a582e69c8bbe182 > > The aggregation files now pass and I can publish the layers. But I am > still wondering if this is the right approach. Or should perhaps the > runtime dimension be treated in the same way as the t- and z-dimensions? Or > should there actually be logic in VariableAdaptor for the R-dimension, > similar to the logic that exists for the Z- and T-dimensions? > > What is your opinion? Thanks for your assistance. > > Kind Regards, > Niels > > -- == GeoServer Professional Services from the experts! Visit http://goo.gl/it488V for more information. == Ing. Daniele Romagnoli Senior Software Engineer GeoSolutions S.A.S. 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