[GRASS-user] r.drain problem when flow reach the border

[Markus Metz]

On Sun, Dec 30, 2012 at 8:59 PM, Milton Cezar Ribeiro
<miltinho.astronauta at gmail.com> wrote:
> Hi Rashad
>
> I tested with the trunk svn, but apparently it still not worked to me.
> Are you able to test with my datased?
>
> https://www.yousendit.com/download/UW16RE9zTkxlM1JBSXNUQw

What are the commands you used? I found
r.drain input=custo_aux_cost output=custo_aux_cost_drain
vector_points=map_target_pt

You need to also provide a direction map with the indir option of r.drain.

Markus M

>
> Thanks!
>
> miltinho
>
> 2012/12/27, Mohammed Rashad <mohammedrashadkm at gmail.com>:
>> Hi Milton,
>>
>> I think this fix will solve the problem[0]. For elevation data there might
>> be cases where no path exists ie, only single pixel is the selected path. I
>> had tested it by myself and it worked.
>>
>> Please apply the patch and let me know.
>>
>> If any problem comes in compilation or doing r.drain let me know. It will
>> be great if you can share the test data you are using in case not working
>> after applying the patch
>>
>> [0] http://trac.osgeo.org/grass/attachment/ticket/1840/r.drain.diff
>> [1] http://trac.osgeo.org/grass/attachment/ticket/1840/drain.c
>>
>>
>> On Thu, Dec 27, 2012 at 2:31 AM, Milton Cezar Ribeiro <
>> miltinho.astronauta at gmail.com> wrote:
>>
>>> Hi Mohamed and Markus
>>>
>>> Mohamed, thanks for your reply, I will wait for a solution within GRASS
>>> :-)
>>>
>>> Markus, thanks for your reply,. Sorry  but I disagree a tiny bit,
>>> because is expected that between a source and target I will find a
>>> solution with the Least Cost path. Do you think that is there any
>>> situation where a least cost between source and target will not be
>>> found? Maybe if other software provide the soluction, although is not
>>> the bestest option, I prefere receive one complete output than a
>>> broken one.
>>>
>>> Happy new year!
>>>
>>> miltinho
>>>
>>> 2012/12/23, Markus Metz <markus.metz.giswork at gmail.com>:
>>> > On Sun, Dec 23, 2012 at 7:07 PM, Milton Cezar Ribeiro
>>> > <miltinho.astronauta at gmail.com> wrote:
>>> >> Dear all,
>>> >>
>>> >> I am running a least cost path analysis combining r.cost and r.drain.
>>> >> But on some cases, when the least cost path between source and target
>>> >> reach the border of my map, r.drain stop on that position, and target
>>> >> point isn´t reached.
>>> >
>>> > This is correct because at the borders, the direction can not be
>>> > determined, the path could lead out of the current region, you can not
>>> > tell.
>>> >
>>> > Running on other softwares the algorithms the
>>> >> source and target is connected using edges without problem.
>>> >
>>> > If in doubt, I would call it a bug in that other software.
>>> >
>>> >>
>>> >> Any hint are welcome.
>>> >
>>> > Try to expand the current region
>>> >
>>> > Markus M
>>> >
>>>
>>>
>>> --
>>> Miltinho - mcr at rc.unesp.br
>>> Laboratório de Ecologia Espacial e Conservação - LEEC
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>>>
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>>>
>>> PG ECO & BIODIV
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>>>
>>> CV
>>> http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4792988H6&mostrarNroCitacoesISI=true&mostrarNroCitacoesScopus=true
>>>
>>> Google citations http://scholar.google.com/citations?user=OWX_2eAAAAAJ
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>>
>>
>>
>> --
>> Regards,
>>    Rashad
>>
>
>
> --
> Miltinho - mcr at rc.unesp.br
> Laboratório de Ecologia Espacial e Conservação - LEEC
> Depto de Ecologia - UNESP - Rio Claro
> Av. 24A, 1515- Bela Vista
> 13506-900 Rio Claro, SP, Brasil
>
> Fone: +55 19 3526-9647 (office)  19 3526-9680 (lab)
> Cel: 19 9853-3220 / 19 9853-5430
>
> Depto Ecologia http://www.rc.unesp.br/ib/ecologia/
>
> PG ECO & BIODIV http://www.rc.unesp.br/ib/ecologia/posbiodiversidade/index.php
>
> CV http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4792988H6&mostrarNroCitacoesISI=true&mostrarNroCitacoesScopus=true
>
> Google citations http://scholar.google.com/citations?user=OWX_2eAAAAAJ