Re: [Qgis-user] Creating DEM from Contour lines
Hi Ulli: I would try converting the contour lines to points first, then generating a DEM. We use this workflow from time to time when we do not have a high quality DEM to work with. Kirk From: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] On Behalf Of Ulrich Kriechbaum Sent: Thursday, November 08, 2018 7:10 AM To: qgis-user@lists.osgeo.org Subject: [Qgis-user] Creating DEM from Contour lines Hello all! I investigate a Glacial Lake Outburst Flood which eroded a lot of material. What i try to do is to backcalculate the event with the simulation tool r.avaflow. For my simulations i need a Pre-Event DEM. I have a Post-Event DEM where the eroded trench is clearly visible. So what i did was to project the Contour lines of the Post-DEM, change them so that the trench is "flattened". Now i try to generate a Pre-Event DEM with these Contour lines. That's the point at which i am struugling. I tried to interpolate the Contour lines (TIN and IDW) but the results were not really satisfying. Does anyone have an idea how to get a nice DEM from contour lines? Best regards, Ulli ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] Creating DEM from Contour lines
Hi, DEMs created from Contour line will have a rice paddy look with steps and flat areas. If this what you are seeing? You could smoothing filtres on the DEM or possible adding data point to the contour lines. Smoothing can make it nicer but not necessarily more accurate. You could perhaps make a densification of the contour lines, extract the vertexes and model that in cloudcompare or Mesh Lab as a mesh could help. Would help to know what is not satisfying about your DEM. Nicolas > Le 8 nov. 2018 à 06:10, Ulrich Kriechbaum a écrit : > > Hello all! > > I investigate a Glacial Lake Outburst Flood which eroded a lot of material. > What i try to do is to backcalculate the event with the simulation tool > r.avaflow. For my simulations i need a Pre-Event DEM. I have a Post-Event DEM > where the eroded trench is clearly visible. So what i did was to project the > Contour lines of the Post-DEM, change them so that the trench is "flattened". > Now i try to generate a Pre-Event DEM with these Contour lines. That's the > point at which i am struugling. I tried to interpolate the Contour lines (TIN > and IDW) but the results were not really satisfying. > > Does anyone have an idea how to get a nice DEM from contour lines? > > Best regards, > > Ulli > ___ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
