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List:       postgis-users
Subject:    Re: [postgis-users] raster extent and performance problem... anyone?
From:       Bborie Park <bkpark () ucdavis ! edu>
Date:       2012-08-23 23:57:27
Message-ID: 5036C367.2030707 () ucdavis ! edu
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From the testing I've done (http://trac.osgeo.org/postgis/ticket/1808)
where I test pixel for pixel what is stored in PostGIS raster versus
what GDAL sees in the source raster, I can't find anything wrong.  But,
only time will tell.

-bborie

On 08/23/2012 04:53 PM, William Kyngesburye wrote:
> 1.9.1 - yes, I saw your discussion about GDAL problems.  Maybe the rounding bug has \
> something to do with it, but even when no bounding box is used from GDAL (like when \
> I just want to query what the extent is of the whole raster), I get the wrong \
> extents and horrible performance. 
> I'd like to at least verify that the PostGIS raster is OK first.  GDAL dev is not \
> really a good option since I need to deploy the extraction scripts on a few \
> computers very soon, and it's best if I can use a packaged distribution. 
> The vrt of the original geotiffs works, so that's what I'll probably be using.
> 
> On Aug 23, 2012, at 1:37 PM, Bborie Park wrote:
> 
> > What version of GDAL are you using?  Could you try GDAL trunk?  I don't
> > trust anything other than trunk (1.9.x or below) due to various bugs.
> > At some point, I'll dig into the PostGIS raster driver...
> > 
> > -bborie
> > 
> > On 08/23/2012 07:01 AM, William Kyngesburye wrote:
> > > almost forgot: PostGIS 2.0.1, on PG 9.1.4.  PPC OS X.
> > > 
> > > On Aug 23, 2012, at 8:46 AM, William Kyngesburye wrote:
> > > 
> > > > I created a raster table for a large area of DEM data, with index and \
> > > > constraints, no overviews.  When I run gdalinfo on the table, it takes about \
> > > > 15m to query to get the extents, which are then wrong. 
> > > > Original 32bit float geotiffs = 27GiB (uncompressed), 84W, 36N to 71W, 45.5N \
> > > > (not complete coverage) 
> > > > In PostGIS = 25GiB, 74W, 33.5N to 61W, 43N
> > > > 
> > > > There are 15936 records in the table, which matches the number of input TIFFs \
> > > > and the tile size I used (actually 22 more than the input), so it looks like \
> > > > all the data was imported. 
> > > > It looks like the data was shifted 10 deg east and 2.5 deg south.
> > > > 
> > > > When I try to extract a region from that with gdal_translate, it takes the \
> > > > 15m to check the extants again, then extracts garbage. 
> > > > I'm just getting started with PG rasters and don't know enough about the SQL \
> > > > needed to check within PG if everything is OK there or not (extents, extract \
> > > > some data to tif) or if it's a GDAL problem. 
> > > > A GDAL vrt of the geotiffs processes quickly and reports the correct extents.
> > > > 
> > > > -----
> > > > William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
> > > > http://www.kyngchaos.com/
> > > > 
> > > > "Time is an illusion - lunchtime doubly so."
> > > > 
> > > > - Ford Prefect
> > > > 
> > > > _______________________________________________
> > > > postgis-users mailing list
> > > > postgis-users@postgis.refractions.net
> > > > http://postgis.refractions.net/mailman/listinfo/postgis-users
> > > 
> > > -----
> > > William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
> > > http://www.kyngchaos.com/
> > > 
> > > "I ache, therefore I am.  Or in my case - I am, therefore I ache."
> > > 
> > > - Marvin
> > > 
> > > 
> > > _______________________________________________
> > > postgis-users mailing list
> > > postgis-users@postgis.refractions.net
> > > http://postgis.refractions.net/mailman/listinfo/postgis-users
> > > 
> > 
> > -- 
> > Bborie Park
> > Programmer
> > Center for Vectorborne Diseases
> > UC Davis
> > 530-752-8380
> > bkpark@ucdavis.edu
> > _______________________________________________
> > postgis-users mailing list
> > postgis-users@postgis.refractions.net
> > http://postgis.refractions.net/mailman/listinfo/postgis-users
> 
> -----
> William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
> http://www.kyngchaos.com/
> 
> All generalizations are dangerous, even this one.
> 
> 
> 

-- 
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark@ucdavis.edu
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