Re: Bugs in r.stream.extract

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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]> =E4=BA=8E2020=E5=B9=B411=E6=9C=8824=E6=97=
=A5=E5=91=A8=E4=BA=8C =E4=B8=8A=E5=8D=887:07=E5=86=99=E9=81=93=EF=BC=9A

> 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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<div dir=3D"ltr">Hi Ken<div><br></div><div>=C2=A0 =C2=A0Many thanks for you=
r reply, I think I made a mistake, the flow accumulation I provided to r.st=
ream.extract did not match the DEM I provided in r.stream.extract.=C2=A0 Th=
e streamline seems based on flow accumulation derived from the provided DEM=
.=C2=A0 =C2=A0</div><div>=C2=A0 =C2=A0=C2=A0</div><div>=C2=A0 =C2=A0But, If=
 I only want to use flow direction to drive streams, which function I shoul=
d use?=C2=A0</div><div><br></div><div>=C2=A0 =C2=A0Is there any chance that=
=C2=A0

r.stream.extract can use flow direction as inputs without DEM?=C2=A0</div><=
div><br></div><div>Thanks</div><div>Ming=C2=A0=C2=A0</div><div>=C2=A0 =C2=
=A0</div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gma=
il_attr">Ken Mankoff &lt;<a href=3D"mailto:[email protected]">mankoff@gmail=
.com</a>&gt; =E4=BA=8E2020=E5=B9=B411=E6=9C=8824=E6=97=A5=E5=91=A8=E4=BA=8C=
 =E4=B8=8A=E5=8D=887:07=E5=86=99=E9=81=93=EF=BC=9A<br></div><blockquote cla=
ss=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid =
rgb(204,204,204);padding-left:1ex">Hi Ming,<br>
<br>
On 2020-11-23 at 09:05 -08, ming han &lt;<a href=3D"mailto:[email protected]=
om" target=3D"_blank">[email protected]</a>&gt; wrote...<br>
&gt; Hope this email finds you well. I got a weird result when using<br>
&gt; r.stream.extract, as shown in the following figure. The back grids is<=
br>
&gt; the flow accumulation layer with a flow accumulation threshold larger<=
br>
&gt; than 1000. while the blue line is the stream generated by<br>
&gt; r.stream.extract. Why the stream from r.stream.extract did not follow<=
br>
&gt; flow accumulation results? And how to fix this problem?<br>
<br>
Is there any chance you can share the raster that includes this region so I=
 can examine it? And the exact command you ran?<br>
<br>
=C2=A0 -k.<br>
<br>
</blockquote></div>

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