[Qgis-user] Manipulating DEM

Rick Rupp palousegeo at outlook.com
Thu Nov 8 12:43:40 PST 2018


Hi Ulli,
If the trench is narrow (in terms of pixels), you can run a smoothing filter over that part of the DEM. Then replace the original trench pixels with those from the smoothed DEM using a conditional statement (gdal_calc with a ‘where’ statement).
Regards, Rick

________________________________
From: Qgis-user <qgis-user-bounces at lists.osgeo.org> on behalf of Ulrich Kriechbaum <ulrichkriechbaum at gmx.at>
Sent: Thursday, November 8, 2018 5:49:12 AM
To: qgis-user at lists.osgeo.org
Subject: [Qgis-user] Manipulating DEM

Dear all!

I investigate a Glacial-Lake Outburst Flood and try to back-calculate the event using the simulation tool r.avaflow. During the event there was a big trench eroded. I have a post-event DEM with a clearly visible eroded trench. What i want to do now is to "flatten" out the trench so that i get a pre-event DEM to start my simulation. What i tried to do is to create the contour lines of the post-event DEM, change them so that they would not show the trench and then create a pre-event DEM out of this contour lines. I already asked the question, if anyone knows how to do that, i already got some nice answers but unfortunately none of the inputs really work for me....

So now to my actual question: Does anyone know another method how to "flatten" out the trench in the DEM? I would be really glad if someone would have an answer, as i have ben struggling a while now with these problem..

Best regards,

Ulli
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