Hi, I'm not sure I made myself clear. I have a "real" river vector dataset of an area. It includes artificial channels also.
This dataset was digitised manually and does not match the extracted river dataset from DTM algorithms in grass (r.stream.extraxt) I need to use the real river vector dataset - hence maybe alter the DTM so that it picks up these "real" rivers (perhaps by using r.carve?) as opposed to what would be created by r.stream.extract. And then when that step is complete, obtain elevation height above the river. Hope this makes sense and I am clear in my explanation. Many thanks all. On Domh 16 MFómh 2018 at 17:21, Johannes Radinger < johannesradin...@gmail.com> wrote: > To me this looks like a flooding-related question, i.e. to extract the > shore lines of a river if it's water level is raised by 1m or 3m? > Maybe (1) extract the raster cells of the elevation map that represents > the river channel, (2) then apply r.grow and (3) then r.mapcalc to subtract > the grown river channel from the original elevation map. > /Johannes > > On Sun, Sep 16, 2018 at 5:16 PM Markus Neteler <nete...@osgeo.org> wrote: > >> Hi, >> >> Shane Carey <careys...@gmail.com> schrieb am Fr., 14. Sep. 2018, 23:02: >> >>> Hi All, >>> >>> Does anyone know is it possible to calculate the elevation above a river >>> channel (actual river network that was digitised as opposed to being >>> extracted from a DTM) from a DTM and create a polygon from it. >>> >>> I need to calculate heights of 1m and 3m above a river channel on both >>> sides of the channel and create a polygon from it. >>> >> >> This isn't clear to me. Could you elaborate? >> >> Best >> Markus >> >> >> Thanks all. >>> >>> Le gach dea ghui, >>> *Shane Carey* >>> *GIS and Data Solutions Consultant* >>> _______________________________________________ >>> grass-user mailing list >>> grass-user@lists.osgeo.org >>> https://lists.osgeo.org/mailman/listinfo/grass-user >> >> _______________________________________________ >> grass-user mailing list >> grass-user@lists.osgeo.org >> https://lists.osgeo.org/mailman/listinfo/grass-user > > -- Le gach dea ghui, *Shane Carey* *GIS and Data Solutions Consultant*
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