Hi Andi,
I had a similar task where I needed to find the elevation value from a
geotiff at the upstream and downstream points of a river line segment.
This thread sums up my approach, based on a kick start from helpful
postgis users:
http://postgis.refractions.net/pipermail/postgis-users/2008-August/020869.html
You'll see within the thread that I link to the code in a google code
svn repo. I think you'll be most interested in the code around line 61
of the raster lookup script here:
http://code.google.com/p/dbsgeo/source/browse/trunk/postgis/hydro_model/scripts/elevation_lookup.py#61
I'd be interested if there is a simpler and faster way to approach
this issue of where to put the values once you've read them
(particularly for the database access since I was needing to go back
to postgis with the looked-up values), if anyone has ideas. What I
found was that writing out a sql insert statement was faster than
hitting the database with updated queries during the lookup routine,
but I may not have been using the psycopg2 driver in the most optimal
way.
Anyway, hope that helps.
Cheers,
Dane
On Sep 26, 2008, at 5:55 AM, [EMAIL PROTECTED] wrote:
Hello,
I have an ESRI ascii raster and would like to get the raster values
at defined x y locations.
At the moment I am capable to load the Raster Dataset and can
perform several operations like querying the Min/Max values, the
origin, the pixelsize and so on....
But is there a function to get the cell value of a raster at a
certain location (x y)????
Has anybody done this before?
Thanks
Andi
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