[fdo-internals] Raster Catalogs (aka Tileindexes)

[Frank Warmerdam]

Greg Boone wrote:
> Hi All,
> 
> The FDO team faces a similar issue with the ATIL based raster provider
> found in the MapGuide Enterprise release. At this time we are planning
> to fix this issue for the next release of MapGuide Enterprise. I would
> hope that we could find a solution that is common to both the ATIL based
> and GDAL based providers.
> 
> The current proposal advocates that the ATIL Raster provider's XML
> configuration document be updated to include the bounds of the
> referenced raster images. Along with this change would come an
> associated change to the API that controls the creation and access of
> the XML configuration document. These additional 'bounds' definitions
> would be used by the provider to filter the list of initial raster
> images based on a spatial filter supplied by the user in an FDO select
> command. Once the selection set of raster images has been determined,
> the raster provider will directly access the images and extract the
> geo-reference information to determine which images to return to the
> client application.
> 
> Since the ATIL and GDAL overrides API and configuration documents are
> virtually identical, a common approach could be agreed on for both
> providers.

Greg,

The proposal looks good to me.  The only downsides I can see are
that linear scanning of the XML config doc may not scale up to hundreds
of thousands of tiles as well as might be hoped, and that folks not
using MapGuide Studio may not have a convenient way of producing the
config files.  However, I don't see either of these as a significant
issue.

Will you or someone at Autodesk be migrating the changes into the
GDAL provider once the change is made for the ATIL based provider?
I'm willing to do some work on this, but I don't honestly grok all this
override stuff and I'd hesitate to do it from scratch.

I would like to help the webstudio guys add raster support including
building the config doc.  It should be pretty easy.

Best regards,
-- 
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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