[prev in list] [next in list] [prev in thread] [next in thread] 

List:       postgis-users
Subject:    [postgis-users] raster extent and performance problem
From:       William Kyngesburye <woklist () kyngchaos ! com>
Date:       2012-08-16 20:13:43
Message-ID: D05BEA6F-7CEA-451A-905E-ABC6A2BF2A70 () kyngchaos ! com
[Download RAW message or body]

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 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


[prev in list] [next in list] [prev in thread] [next in thread]