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List:       grass-user
Subject:    Re: [GRASS-user] patching vectors - some are not patched
From:       Ken Mankoff <mankoff () gmail ! com>
Date:       2018-11-19 16:22:56
Message-ID: 87sgzxujdr.fsf () geus3064linuxwsm ! geus ! dk
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On 2018-11-19 at 16:59 +0100, Markus Metz <markus.metz.giswork@gmail.com> wrote:

> looking at your aim: get basins for all outlets, you could also use
> 1. r.stream.extract with stream_vector as output
> outlets have category value 2 in layer 2
> 2. extract the outlets with v.extract lyer=2 type=point cats=2
> 3. use the outlets as input for r.stream.basins

Yes this is my main aim, but as usual things are getting more complicated.

It turns out I cannot use r.watershed over sub-regions (even if I overlap and then \
crop) because it produced bad output due to catchments meeting the edge of regions. \
So I'm going back to r.terraflow.

r.terraflow means I don't have access to the stream maps that you're suggesting I \
use. I also have "direction" in a different format than all the other tools want, but \
I can convert it. I'm not sure what to do about the interior basins that r.terraflow \
leaves unlike r.watershed which fills them... I think I'll run all my \
'r.water.outlets', generate my raster basins, then flood each basin so that the \
interior basins are now included.

All this is complicated by the fact that I'm working with a 4.5 billion cell raster \
(90,000 x 50,000) with ~100,000 outlets (catchments). I have it running fairly fast \
on my laptop thanks to GNU parallel and WIND_OVERRIDE.

Work is in progress...

  -k.
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