[GRASS-user] r.stream.extract - stream dir map output

[M S]

Thanks, I'll give it a shot.

Mark

2009/11/16 Markus Metz <markus.metz.giswork at googlemail.com>:
>
>
> Jarosław Jasiewicz wrote:
>>
>> M S pisze:
>>>
>>> As an output from r.streams.extract, I'm getting a stream direction
>>> map that is only along the stream network, and null everywhere else.
>>> >From the manual, it seems the direction map needs to be for the entire
>>> study area.  I am looking to feed the streams and direction map into
>>> the r.stream.basins module.
>>>  Since I'm on GRASS 6.4RC5, I dont have MFD option in my r.watershed,
>>> so I rely upon r.stream extract to output the stream network and the
>>> direction map.  I had seen a portion in the notes stating "Nowadays f
>>> direction map comes from r.stream.extract must be patched by direction
>>> map from r.watershed. (with r.patch).
>>>
>>> I wouldnt think I could patch the SFD direction output from
>>> r.watershed with the MFD stream direction map to create a direction
>>> map for the entire study area.  Is there another solution to use MFD?
>>>
>>
>> if grass64 really do not have MFD (i'm suprised!) the only solution is to
>> compile grass 65 from source
>
> grass64 has MFD in r.terraflow. You can use r.terraflow + r.dominant_dir.m +
> r.calc_terraflow_dir.m (grass-addons) in order to get the main drainage
> direction for MFD flow, use r.terraflow flow accumulation and the filled
> elevation map produced by r.terraflow as input to r.stream.extract, then
> patch the new flow directions into the main drainage direction extracted
> with the addon tools.
>
> You can also use flow accumulation from r.watershed with SFD as input to
> r.stream.extract and patch the flow directions of r.stream.extract into
> r.watershed flow directions, these are compatible. But note ticket #807.
>
> As Jarek said, best would be to use r.watershed in grass65 instead.
>
> Hope that helps,
>
> Markus M
>
>