[fdo-internals] Raster Catalogs (aka Tileindexes)

[Frank Warmerdam]

Folks,

Jason Birch and I are interested in some mechanism to support raster
catalogs (or tileindexes in mapserver-speak) for the GDAL raster provider.
That is a way of listing a whole bunch of files, along with their spatial
footprint in a single catalog so that the raster provider only has to actually
open the files of interest for the current request.

Does such a thing exist for the other (ATIL based) raster provider?

Is there a standard scheme suggested for implementing such a thing?

My thinking was that it should be possible to use any FDO feature source
as the catalog and that the catalog would primarily devolve down to two
things.

   - A column with the filename for the raster (possibly a relative path)
   - A polygon geometry with is the footprint of the raster.

The already existing "gdaltindex" utility can create shapefiles in this
form for a set of rasters.  I'd suggest just hardcoding things to use
shapefiles, but I suspect some people will want to use more sophisticated
raster catalogs in an RDBMS and it just doesn't seem like the right
FDO way of doing things.

As long as we come up with a scheme that isn't too complicated, I'm happy
to implement it for the GDAL based raster provider.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org