The table contains SRTM3 data. What I would really like to do is
retrieve the altitude for any given lat/lon. We currently have
scientific codes that read the SRTM3 flat file into an array and
interpolate the value for the lat/lon pair. We would like to retrieve
the data from a database instead of flat file thinking the performance
would be better. However, the times retrieving the array from the
database are many orders of magnitude worse than just reading the array
in from a flat file.
On 10/12/2011 8:34 PM, Pierre Racine wrote:
If you want to get all the values for every pixel do:
SELECT (ST_DumpAsPolyogns(rast)).val
FROM your table
Can I ask why you want to do that? Normally people want to extract values
intersecting with a polygon or a point.
You can also get the histogram of the raster using ST_Histogram().
Pierre
________________________________________
From: [email protected]
[[email protected]] On Behalf Of elliott
[[email protected]]
Sent: Wednesday, October 12, 2011 9:04 AM
To: PostGIS Users Discussion
Subject: [postgis-users] Retrieving Data from PostGIS Raster using ST_Value
Hello Everyone,
I am very new to using PostGIS Raster. I need to retrieve data fields
from a tile loaded into the database. Using ST_Height and ST_Width, I
get the number of rows and columns and iterate over these using the
ST_Value to retrieve the data. This is extremely slow taking 1/2 hour
to get all of the data required. Is there a faster way to accomplish this?
Thanks!
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