Re: [Qgis-user] Merging DEMs

[Micha Silver]

On 29/05/2014 16:42, Mark Seibel wrote: Hi. On Thu, May 29, 2014 at 9:25 AM, Randal Hale <rjh...@northrivergeographic.com> wrote: I have two Digital Elevation Models - Imagine a square cut into two equal triangles. No matter how I do it - One DEM overwrites the other one so I'm only ever getting half of the elevation model I want when I merge them. ...  Thoughts or ideas? Randy Is there a GRASS function in QGIS for r.patch?  It uses both datasets, and uses one to fill the NULL values of another.  Would probably have to make sure the computational region is set to accommodate the extent of merging both DEMs (maybe not necessary if r.patch doesnt regard region settings). The way to do this in GRASS is with the isnull() function in r.mapcalc Here's an example from the man page: Example: The users wants the NULL-valued cells to be treated like zeros. To add maps A and B (where B contains NULLs) to get a map C the user can use a construction like: C=A + if(isnull(B),0,B) And,as Mark mentioned, be sure to set your region to cover both maps from the start Mark   This mail was received via Mail-SeCure System. _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user This mail was received via Mail-SeCure System. -- Micha Silver GIS Consulting 052-3665918 http://www.surfaces.co.il

_______________________________________________
Qgis-user mailing list
Qgis-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-user