[GRASS-user] Interpreting r.stream.extract output (was: r.stream.extract Syntax Problem)

[Rich Shepard]

On Mon, 9 Apr 2012, Markus Metz wrote:

> The computational region should be aligned to the DEM in order to get
> accurate results. Aligning to the resolution of the DEM is not enough,
> i.e. you should use g.region align=DEM instead of g.region res=XXX -a.
> r.stream.extract should work if only a subregion is to be analysed by
> setting the computational region accordingly and/or creating a MASK e.g.
> for a specific basin.

Markus, madi, et al.:

   The region does need to be set with a mask (in my case, and based on the
v.to.rast output of the individual subbasins).

   The last advice in the example on the manual page is to compare the
weighted and unweighted extracted stream maps and "see which looks better."
As a newcomer to this module I have no experience on what "better" looks
like.

   Attached are two .pdf files. One shows the weighted output streams, the
other the unweighted output streams. Both have the vector streams overlaid
on them. The weighted output has a solid yellow background and I don't know
what that represents.

   Given these two maps, what do you advise me to use as input to r.basin?

Many thanks,

Rich
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