<div><div dir="auto">Hi,</div><div dir="auto"><br></div><div dir="auto">I'm not sure I made myself clear. I have a "real" river vector dataset of an area. </div><div dir="auto">It includes artificial channels also.</div><div dir="auto"><br></div><div dir="auto">This dataset was digitised manually and does not match the extracted river dataset from DTM algorithms in grass (r.stream.extraxt)</div><div dir="auto"><br></div><div dir="auto">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.</div><div dir="auto"><br></div><div dir="auto">And then when that step is complete, obtain elevation height above the river.</div><div dir="auto"><br></div><div dir="auto">Hope this makes sense and I am clear in my explanation.</div><div dir="auto"><br></div><div dir="auto">Many thanks all. </div><div dir="auto"><br></div><div class="gmail_quote"><div>On Domh 16 MFómh 2018 at 17:21, Johannes Radinger <<a href="mailto:johannesradinger@gmail.com">johannesradinger@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>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?<div>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. </div></div><div><div>/Johannes</div></div><br><div class="gmail_quote"><div>On Sun, Sep 16, 2018 at 5:16 PM Markus Neteler <<a href="mailto:neteler@osgeo.org" target="_blank">neteler@osgeo.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div>Hi,<br><br><div class="gmail_quote"><div>Shane Carey <<a href="mailto:careyshan@gmail.com" rel="noreferrer" target="_blank">careyshan@gmail.com</a>> schrieb am Fr., 14. Sep. 2018, 23:02:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div>Hi All,</div><div><br></div><div>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. <br></div><div><br></div><div>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.</div></div></blockquote></div></div><div dir="auto"><br></div><div dir="auto">This isn't clear to me. Could you elaborate?</div><div dir="auto"><br></div><div dir="auto">Best</div><div dir="auto">Markus</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div>Thanks all.<br></div><div><br></div><div><div><div class="m_-8945900907715443022m_6169360278670167338m_2339673023995376465m_-8196890261203296796gmail_signature" data-smartmail="gmail_signature"><div><div><div><div><div><div>Le gach dea ghui,<br></div><div><span style="color:rgb(61,133,198)"><b><span style="background-color:rgb(255,255,255)"><i>Shane Carey</i></span></b></span></div><div><span style="color:rgb(61,133,198)"><b><span style="background-color:rgb(255,255,255)"><i>GIS and Data Solutions Consultant</i></span></b></span><br></div></div></div></div></div></div></div></div>
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</blockquote></div></div><div dir="ltr">-- <br></div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>Le gach dea ghui,<br></div><div><span style="color:rgb(61,133,198)"><b><span style="background-color:rgb(255,255,255)"><i>Shane Carey</i></span></b></span></div><div><span style="color:rgb(61,133,198)"><b><span style="background-color:rgb(255,255,255)"><i>GIS and Data Solutions Consultant</i></span></b></span><br></div></div></div></div></div></div></div>