Hi Ken Many thanks for your reply, I think I made a mistake, the flow accumulation I provided to r.stream.extract did not match the DEM I provided in r.stream.extract. The streamline seems based on flow accumulation derived from the provided DEM.
But, If I only want to use flow direction to drive streams, which function I should use? Is there any chance that r.stream.extract can use flow direction as inputs without DEM? Thanks Ming Ken Mankoff <[email protected]> 于2020年11月24日周二 上午7:07写道： > Hi Ming, > > On 2020-11-23 at 09:05 -08, ming han <[email protected]> wrote... > > Hope this email finds you well. I got a weird result when using > > r.stream.extract, as shown in the following figure. The back grids is > > the flow accumulation layer with a flow accumulation threshold larger > > than 1000. while the blue line is the stream generated by > > r.stream.extract. Why the stream from r.stream.extract did not follow > > flow accumulation results? And how to fix this problem? > > Is there any chance you can share the raster that includes this region so > I can examine it? And the exact command you ran? > > -k. > >
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