Would you be able to give me an example of this please? This software is really really good. I absolutely love it. Keep up the great work!!
Le gach dea ghui, *Shane Carey* *GIS and Data Solutions Consultant* On Sat, Sep 22, 2018 at 3:25 PM, johannesradinger < johannesradin...@gmail.com> wrote: > You could also try larger size parameters depending on the degree of > filtering you want to achieve > > > > Sent from my Samsung Galaxy smartphone. > > -------- Original message -------- > From: Shane Carey <careys...@gmail.com> > Date: 22/09/2018 15:47 (GMT+01:00) > To: johannesradinger <johannesradin...@gmail.com> > Cc: Markus Neteler <nete...@osgeo.org>, GRASS user list < > grass-user@lists.osgeo.org> > Subject: Re: [GRASS-user] Elevation above a river > > No worries, I'm not seeing any differences in the original and the > filtered cells. I've tried mode and max methods > > Thanks > > Le gach dea ghui, > *Shane Carey* > *GIS and Data Solutions Consultant* > > On Sat, Sep 22, 2018 at 2:39 PM, johannesradinger < > johannesradin...@gmail.com> wrote: > >> Sorry I ment method=mode or median as stated by Markus N. >> >> >> >> Sent from my Samsung Galaxy smartphone. >> >> -------- Original message -------- >> From: Shane Carey <careys...@gmail.com> >> Date: 22/09/2018 15:05 (GMT+01:00) >> To: Johannes Radinger <johannesradin...@gmail.com> >> Cc: Markus Neteler <nete...@osgeo.org>, GRASS user list < >> grass-user@lists.osgeo.org> >> Subject: Re: [GRASS-user] Elevation above a river >> >> This works a treat - super stuff - thanks Johannes. >> >> Could you point me in the direction of an algorithim with Grass that can >> do the following: >> >> # Clean some of the spurious cells etc. (using some kind of neighbourhood >> filtering) >> >> Thanks very much >> >> Le gach dea ghui, >> *Shane Carey* >> *GIS and Data Solutions Consultant* >> >> On Sun, Sep 16, 2018 at 8:46 PM, Johannes Radinger < >> johannesradin...@gmail.com> wrote: >> >>> That is were the third step should follow, i.e. using r.mapcalc to >>> identify all the cells that are 1m higher than the grown river >>> (irrespective in which distance from the river these cells are located). >>> The rasterized area could then be translated into a vector format using >>> r.to.vect. >>> >>> Here a small example of how the working flow could be using the North >>> Caroline example dataset: >>> ############## >>> # Set region >>> g.region raster=elevation@PERMANENT >>> >>> # Extract elevation of the streams >>> r.mapcalc --o expression="streams_elevation = if( >>> streams_derived@PERMANENT, elevation@PERMANENT,null())" >>> >>> # Grow stream_elevation map by a some hundred meters >>> r.grow -m --overwrite input=streams_elevation >>> output=streams_elevation_grow radius=500 >>> >>> # Calculate difference between original elevatoin and stream channel >>> elevation >>> r.mapcalc expression="stream_elevation_diff = elevation@PERMANENT - >>> streams_elevation_grow" --overwrite >>> >>> # Extract areas that are than x meters higher than stream channel >>> elevation >>> r.mapcalc expression="stream_elevation_diff_smaller1 = if( >>> stream_elevation_diff < 1,1,null())" --overwrite >>> >>> # Maybe here it needs some cleaning of spurious cells etc. (using some >>> kind of neighbourhood filtering) >>> >>> # Raster areas to a vector area (with smoothed corners; s-flag) >>> r.to.vect -s --overwrite input=stream_elevation_diff_smaller1 >>> output=stream_elevation_diff_smaller1_area type=area >>> ############## >>> >>> HTH >>> /Johannes >>> >>> On Sun, Sep 16, 2018 at 8:53 PM Shane Carey <careys...@gmail.com> wrote: >>> >>>> Hey Johannes, >>>> >>>> Thanks for your reply. How does r.grow work if let's say the height >>>> above the river reaches 1m at 3meters away from the river. And in an other >>>> area it reaches the 1meter height at 2meters away from the river. Is it >>>> able to follow that line? >>>> >>>> Thanks >>>> >>>> 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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