VOTable for Images

[CresitelloDittmar, Mark]

All,

In my presentation at the interop (DM session), I mentioned that the
VOTable serializations of the 2D and 4D image fail validation.

I'm not terribly surprised (it is VO*Table* after all), but I have some
small hope of working up to some usage work on the Cube-Image in the near
future and am not sure what the strategy is for serializing/annotating
image datasets.

Looking for suggestions..

Basically, I'm currently using the same mode that I do with tabular
datasets.  Include the header metadata, describe the content, point to the
FITS file.

      <FIELD ID="_col-image" name="image" datatype="int"/>
      <DATA>
        <FITS extnum="0">
          <STREAM
href="file:///data/vao/staff/mcd/docs/models/dm/Cube/examples/src/chandra_2Dsky_image.fits"/>
        </FITS>
      </DATA>

1) obviously, there is no field named "image" in the dataset, I could use
the block name, but it's still a hack
2) extnum="0"
The VOTable spec is pretty clear that the extensions are "numbered from 1
up, the main header being numbered 0".
So, it's no surprise that I get the following validation error on this:
(using votlint in stilts_3.0-9)
   ERROR (l.293, c.26): cvc-minInclusive-valid: Value '0' is not
facet-valid with respect to minInclusive '1' for type 'positiveInteger'.
   ERROR (l.293, c.26): cvc-attribute.3: The value '0' of attribute
'extnum' on element 'FITS' is not valid with respect to its type,
'positiveInteger'.
   ERROR (l.294, c.112): Non-positive extension number extnum=0
   WARNING (l.294, c.112): Read error for external stream
uk.ac.starlink.table.TableFormatException: Can't read FITS header

And, if I point it at a non-table HDU in later extensions...
   WARNING (l.294, c.93): Read error for external stream
java.io.IOException: No table HDU at extension 2

I suppose I could do it with the <BINARY> node, but it'd be nice for the
redirect to work.

Mark
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