[gdal-dev] hdf5image metadata problems

[Alex Mantaut]

Antonio,
           Ok, I understand the asociation between the raster band and the
metadata, but if you have to explicitally ask for the raster band in order
to get the metadata there is an inconsistency between the interface to get
metadata from hdf5dataset and hdf5imagedataset... In hdf5dataset
GetMetadata() returns the metadata asociated to the all the subdatasets
without need to explicitally ask for the raster band, but in
hdf5imagedataset you have to explicitally ask for the raster band in order
to get the metadata...
           IMHO the interface should be the same in both cases, in that case
hdf5imagedataset should retrieve the metadata asociated to the subdataset
directly via GetMetadata()...

regards

PS: Your english is fine, i hope you can understand my lousy english... If
you can't explain something in english you can also write in italian to my
mail, the we can send a translated message with the conclusions to the list


2011/6/16 Antonio Valentino <antonio.valentino at tiscali.it>

> Hi Alex,
>
> Il giorno Thu, 16 Jun 2011 10:05:42 -0300
> Alex Mantaut <alexmantaut at suremptec.com.ar> ha scritto:
>
> > Hi Antonio,
> >
> > For what I discussed with Frank it seemed that the expected behavior
> > was to get the only the data asociated to that subdataset (plus some
> > aditional data from root and the other groups) I wasn't sure untill
> > you confirmated...
> >
> > Well, right now when I open a specific subdataset it gets only the
> > raster band asociated to that dataset, but when I try to open the
> > metadata (with GetMetadata() or GetMetadataItem()) from that
> > subdataset it opens the metadata from all the groups (as expected)
> > but it doesn't get the metadata asociated to that subdataset... Did I
> > do something incorrectly when opening the metadata from the
> > subdataset?
> >
> >  The line suggested in the ticket:
> >         ReadGlobalAttributes( TRUE );
> >
> > Was a way to get around the problem, but now that I'm sure that
> > hdf5imagedataset doesn't need to read all the metadata, it's not a
> > suitable solution to the defect...
> >
> > Right now I found another way to get the metadata from the
> > subdataset, by getting the rasterband first, and then asking for the
> > metadata asociated to that raster band ( it seems a overly convoluted
> > to get the metadata asociated to that subdataset...) I'm guessing
> > that the expected behavior is to get the information directly through
> > GetMetadata() directly...
> >
> > regards
> >
>
> Well, IMHO it is not convoluted. Associating "HDF5 dataset" metadata
> tho the GDAL raster band just reflects the original HDF5 structure.
>
> Even if HDF5 and GDAL data model are quite different we can assume,
> IMHO, the following correspondence:
>
> HDF5 file    --> GDAL dataset (HDF5Dataset class)
> HDF5 Group   --> None (metadata are associated to GDAL dataset)
> HDF5 Dataset --> GDAL Raster Band
>
> HDF5 file can contain several datasets (with arbitrary shape) so the
> GDAL subdataset mechanism is used to tell to the HDF5ImageDataset class
> which is the "HDF5 dataset" the have to be mapped onto the GDAL raster
> band.
>
> I hope this is not too much confusing, with my poor english I'm not
> able to explain it better :).
>
>
> regards
>
> >
> > 2011/6/15 Antonio Valentino <antonio.valentino at tiscali.it>
> >
> > > Hi Frank, hi Alex,
> > >
> > > Il 15/06/2011 22:34, Frank Warmerdam ha scritto:
> > > > On 11-06-15 03:50 PM, Alex Mantaut wrote:
> > > >> Hi Frank:
> > > >>              Thanks for the swift reply.
> > > >>               Right now it opens the metadata asociated to the
> > > >> root, and also
> > > >> the metadata asociated with all the other groups, but it doesn't
> > > >> open
> > > the
> > > >> metadata asociated to the specified element (bug?)
> > > >
> > > > Alex,
> > > >
> > > > It sounds like a defect to me, yes.
> > > >
> > > > I would suggest filing a ticket that carefully documents the
> > > > problem with a supporting example file.
> > > >
> > > > Best regards,
> > >
> > > The current behavior looks fine to me.
> > >
> > > If one opens a specific subdataset then only one "HDF5 dataset
> > > object" can be accessed and it is mapped on GDAL raster bans n. 1.
> > > All other "HDF5 dataset object" in the h5 file are ignored by the
> > > HDF5ImageDataset so there is no reason IMHO to make their metadata
> > > available in some manner.
> > >
> > > Metadata associated to all HDF5 groups (including the root one) are
> > > available in any case and accessible via GDAL dataset metadata.
> > >
> > > my two cents
> > >
> > > --
> > > Antonio Valentino
>
>
> --
>  Antonio Valentino
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>



-- 
--
     Alex Mantaut
SUR Emprendimientos Tecnológicos

Perú 345  Piso 5to Oficina "B" (C1067AAG)
Ciudad de Buenos Aires, Argentina
Tel. +54 (11) 4342-2976/84
alexmantaut at suremptec.com.ar
www.suremptec.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20110616/4431ca93/attachment.html