[postgis-users] Raster Support...

[Stephen Frost]

* Paul Ramsey (pramsey at refractions.net) wrote:
> Well, I had a use for raster-in-the-database myself recently, but it  
> was quite focussed on analytical requirements, to the extent of doing  
> something like "grass in the database", with SQL as the interface.   
> But that is not Oracle GeoRaster, it's something else again.
> 
> Last time this subject came up, I asked for use cases: once you get  
> your rasters in the database, what are you going to do with them?   
> (Suck them out again and put them on a screen?  Go get a WMS server,  
> you wacky lunatic, stop using your database like a file system!)
> 
> To repeat:  once you get your rasters in the database, what are you  
> going to do with them?

As I mentioned, I havn't really tried to get the rasters working with
the existing systems yet so maybe I'm jumping in at the wrong point
here.  Honestly, I didn't realize this thread was about putting the
actual images in the database. :)

My general feeling is that rasters themselves would actually be on
a filesystem but the information about them would exist in the 
database.  I was thinking the information about rasters would be
different in some respects to the information about vectors and I
assumed 'Raster Support in PostGIS' was about handling that 
difference.

The things I'm thinking about stem a bit more from the GRASS side of
things (I think anyway, having not used GRASS all that much myself..):
obviously the size/shape of the raster image (I guess this is really
just a polygon) but then other things like the orientation (alright,
maybe that's just the SRID), the slope (perhaps just the altitude at the
different corners maybe?  Not sure), the elevation (PostGIS has a 'z'
though), etc...

Overall, that a MapServer or GRASS-type application could use PostGIS
for finding the information about rasters, including their on-disk
location and if they're relevent given the current extent or what have
you, and then pull the actual rasters from the filesystem directly.

Just my initial thoughts, once I start working on adding in rasters to
what I'm doing with PostGIS currently I may be able to provide more
useful and sensible input. :)

	Thanks,

		Stephen
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