ogr tileindex with postgis?

[Neil Best]

On Thu, 20 Sep 2007 12:47:31 -0400, Frank Warmerdam <warmerdam at POBOX.COM> wrote:

>Neil Best wrote:
>> Is it possible to use a PostGIS table as a tileindex?  The docs seem to
>> indicate so, but I could not find an example of how to connect to
>> PostGIS through CONNECTIONTYPE OGR. 
>
>Are you wanting to use postgis as a tileindex for a raster or a vector
>layer?  I only have experience doing this for raster layers, but it might
>also work for vector layers.
>

Yes, Frank, it is for raster layers.  Gregor was quite right to wonder what
the advantage of tileindexing vector layers if PostGIS is being used properly.

>Generally if you want to use postgis for a tileindex, you need to create
>a seperate tileindex layer and then reference that layer by name in the
>TILEINDEX keyword of the tiled layer.

It worked like a charm!  (Except now something is wrong with my legends . .
. gremlins!)  I never would have thought of referring to a layer from
another layer and I don't recall mention of it in my scouring of the docs. 
Are there other applications/examples of this technique?  

I have some ideas about how to use this table as a unified raster catalog. 
As I understand it a TILEINDEX must be in the same projection as the rasters
to which it refers.  I am imagining that I can still use this table for a
heterogeneous collection (e.g. NAIPs are in UTM zones) because I can set up
views that provide the tile geometry in the proper SRS while still
maintaining a geometry column in our default SRS*.  Furthermore this will
allow me to define a cross-section of the collection using SQL which will be
useful in accessing rasters along the time dimension and any other way based
on the path/file or any additional attributes.  This table will serve an
additional purpose in keeping track of automated, near-real-time data
ingests.  Frank, maybe your
experiences have taken you in similar directions.  I presume that you will
be in Victoria next week -- maybe I could corner you to discuss this
further.  Thanks for the tip; this will be very useful.

Neil


*Which happens to be an Albers Equal Area for the continental US that has no
EPSG code.  I find this strange because I believe that it comes from the
USGS and is widely used, but what do I know?  I'll attach the WKT for
inspection -- maybe it could be adopted if there was enough interest.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: aeaConus.wkt
Type: application/octet-stream
Size: 152 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/mapserver-users/attachments/20070920/72c0c2cd/attachment.obj>