[postgis-users] Raster Support...
sfrost at snowman.net
Fri Aug 25 11:32:00 PDT 2006
* 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
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'
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. :)
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