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<TITLE>[fdo-internals] Raster Catalogs (aka Tileindexes)</TITLE>
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<DIV>Hi Frank, </DIV>
<DIV> </DIV>
<DIV>Here my thoughts on this. A raster catalog does not need to be exposed at
the API level. For example, one way to do this would be to "connect" the raster
provider to a directory containing a large number of rasters. Internally, the
provider could index these in whatever way it wants.</DIV>
<DIV> </DIV>
<DIV>I would personally use an SDF file for the spatial index -- like you say,
insert a polygon corresponding to the bounds of the raster and use the raster
name (or index) as ID property. An SHP file will probably work fine too, I've
seen lots of raster catalogs stored in shp files before.</DIV>
<DIV> </DIV>
<DIV>One thing I always wondered is whether it's worth it to persist the index
into a file or is it easier to initialize it the first time an FDO connection is
opened and then keep it in memory until the connection is closed. Given that FDO
connections remain open for a while, it seems like keeping it in memory is not
such a bad idea, and avoids the trouble of dealing with an index file.</DIV>
<DIV> </DIV>
<DIV>Traian</DIV></DIV>
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<DIV><FONT size=2>-----Original Message----- <BR><B>From:</B>
fdo-internals-bounces@lists.osgeo.org on behalf of Frank Warmerdam
(External) <BR><B>Sent:</B> Wed 1/24/2007 10:42 PM <BR><B>To:</B> FDO
Internals Mail List <BR><B>Cc:</B> Jason Birch <BR><B>Subject:</B>
[fdo-internals] Raster Catalogs (aka Tileindexes)<BR><BR></FONT></DIV>
<P><FONT size=2>Folks,<BR><BR>Jason Birch and I are interested in some
mechanism to support raster<BR>catalogs (or tileindexes in mapserver-speak)
for the GDAL raster provider.<BR>That is a way of listing a whole bunch of
files, along with their spatial<BR>footprint in a single catalog so that the
raster provider only has to actually<BR>open the files of interest for the
current request.<BR><BR>Does such a thing exist for the other (ATIL based)
raster provider?<BR><BR>Is there a standard scheme suggested for implementing
such a thing?<BR><BR>My thinking was that it should be possible to use any FDO
feature source<BR>as the catalog and that the catalog would primarily devolve
down to two<BR>things.<BR><BR> - A column with the filename for
the raster (possibly a relative path)<BR> - A polygon geometry
with is the footprint of the raster.<BR><BR>The already existing "gdaltindex"
utility can create shapefiles in this<BR>form for a set of rasters. I'd
suggest just hardcoding things to use<BR>shapefiles, but I suspect some people
will want to use more sophisticated<BR>raster catalogs in an RDBMS and it just
doesn't seem like the right<BR>FDO way of doing things.<BR><BR>As long as we
come up with a scheme that isn't too complicated, I'm happy<BR>to implement it
for the GDAL based raster provider.<BR><BR>Best
regards,<BR>--<BR>---------------------------------------+--------------------------------------<BR>I
set the clouds in motion - turn up | Frank Warmerdam,
warmerdam@pobox.com<BR>light and sound - activate the windows | <A
href="http://pobox.com/~warmerdam">http://pobox.com/~warmerdam</A><BR>and
watch the world go round - Rush | President OSGeo, <A
href="http://osgeo.org">http://osgeo.org</A><BR><BR>_______________________________________________<BR>fdo-internals
mailing list<BR>fdo-internals@lists.osgeo.org<BR><A
href="http://lists.osgeo.org/mailman/listinfo/fdo-internals">http://lists.osgeo.org/mailman/listinfo/fdo-internals</A><BR></FONT></P></BLOCKQUOTE>
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