Re: Bugs in r.stream.extract

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And another problem I got is that the flow accumulation I got from
r.accumulate and r.watershed is different when r.accumulate using flow
direction from r.watershed.  Again is there anyway r.watershed supports
using flow direction, so we can get the consistent result.

We need this when we need to adjust the flow direction from  r.watershed or
r.stream.extract. and then we need to determine new flow accumulation with
an adjusted flow direction dataset.  If the result is inconsistent, not
sure what is the solution is.

Cheers
Ming

ming han <[email protected]> =E4=BA=8E2020=E5=B9=B411=E6=9C=8825=E6=97=A5=
=E5=91=A8=E4=B8=89 =E4=B8=8A=E5=8D=886:38=E5=86=99=E9=81=93=EF=BC=9A

> 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 s=
o
>> I can examine it? And the exact command you ran?
>>
>>   -k.
>>
>>

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<div dir=3D"ltr">And another problem I got is that the flow accumulation I =
got from r.accumulate and r.watershed is different when r.accumulate using =
flow direction from r.watershed.=C2=A0 Again is there anyway r.watershed su=
pports using flow direction, so we can get the consistent result.=C2=A0<div=
><br></div><div>We need this when we need to adjust the flow direction from=
=C2=A0

 r.watershed or r.stream.extract. and then we need to determine new flow ac=
cumulation with an adjusted flow direction dataset.=C2=A0 If the result is =
inconsistent, not sure what is the solution is.=C2=A0</div><div><br></div><=
div>Cheers</div><div>Ming=C2=A0</div></div><br><div class=3D"gmail_quote"><=
div dir=3D"ltr" class=3D"gmail_attr">ming han &lt;<a href=3D"mailto:dustmin=
[email protected]">[email protected]</a>&gt; =E4=BA=8E2020=E5=B9=B411=E6=9C=8825=
=E6=97=A5=E5=91=A8=E4=B8=89 =E4=B8=8A=E5=8D=886:38=E5=86=99=E9=81=93=EF=BC=
=9A<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px =
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"=
ltr">Hi Ken<div><br></div><div>=C2=A0 =C2=A0Many thanks for your reply, I t=
hink I made a mistake, the flow accumulation I provided to r.stream.extract=
 did not match the DEM I provided in r.stream.extract.=C2=A0 The 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 wan=
t to use flow direction to drive streams, which function I should 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]" target=3D"_bl=
ank">[email protected]</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></d=
iv><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord=
er-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>
</blockquote></div>

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