[GRASS-user] r.stream.extract: map mis-match error

[Markus Metz]

On Fri, Apr 20, 2012 at 7:01 PM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> On Fri, 20 Apr 2012, Markus Metz wrote:
>
>> Try to set the region and MASK before the analysis, then don't modify
>> these settings during the analysis. Something like
>>
>> g.region vect=basins align=dem_proj
>> g.region res=10m -a
>> r.resamp.stats in=dem_proj out=dem_10m method=average -w
>> v.to.rast in=basins out=MASK type=area use=val val=1
>> r.watershed elevation=dem_10m acc=dem_10m.acc basin=dem_10m.basin
>> threshold=150000
>> r.mapcalc "dem_10m.acc.w = dem_10m.acc * weight"
>> r.stream.extract elevation=dem_10m acc=dem_10m.acc.w
>> stream_rast=dem_10m.streams stream_vect=dem_10m_streams threshold=???
>
>
>  My only modifications to the above were to run r.param.scale after
> r.watershed and r.mapcalc to calculate weight from the r.param.scale
> tangential curve output maps before calling r.mapcalc to apply the weights.
> Could these be problematic?

I guess so because you said that r.stream.extract works with the
unweighed accumulation map. How exactly did you calculate the weight?
BTW, I checked the example script in the manual of r.stream.extract
and it works in 6.4.3 and 7.0.

Markus M

>
>  The results are still
>
> GRASS 6.5.svn :~/grassdata > r.stream.extract
> elev=dem_10m acc=dem_10m.acc.w stream_rast=dem_10m.rstreams.w
> stream_vect=dem_10m.vstreams.w thresh=1000 --o
> Load input maps and get start points...
> ERROR: Accumulation map does not match elevation map!
>
>  I'm completely puzzled ... and a bit frustrated that the same error is
> thrown so consistently.
>
>
> Rich
>
>
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