RASTER layer functionality, a SWAQ

[Frank Warmerdam]

John Novak wrote:
> I have a large number of rows containing metadata about rater files 
> sitting in a PostGIS table.  Each row is associated with a georeferenced 
> file sitting in a file system, and the row contains polygon geometry 
> representing the footprint of the raster.  The rows also contain many 
> other attributes that I'd like to use to filter the displayed rasters.
> 
> Having the functionality of the RASTER layer, but using a PostGIS table 
> as a source for features rather than a SHAPEFILE would be a very useful 
> thing, at least in my case.
 >
> What's the opinion regarding
> 
> 1. the overall usefulness of such a beastie
> 
> and
> 
> 2.  the complexity of actually implementing said beastie, given that 
> it's a combination of the functionality of a PostGIS layer and a RASTER 
> layer ?
> 
> I admit I have not done my homework and really examined the code for 
> these two layers.

John,

It is currently possible to use a postgis table as a "tile index" for
a raster layer.  To do so, configure the postgis table as a distinct layer,
and use the name of that layer in the TILEINDEX keyword of your raster layer
instead of the name of an external shapefile.

The raster layer will do a spatial query on the tileindex table to get
a list of rasters to plot.

I'm a bit fuzzy on how you would do other sorts of query operations.
It is possible a FILTER on the tileindex layer will be preserved as
part of the tileindex query, but I'm not absolutely sure.  Of course,
you could put complex query logic right into your DATA statement on
the postgis layer.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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