[GRASS-user] r.water.outlet: no map displayed

[Helmut Kudrnovsky]

Rich Shepard wrote
> On Mon, 3 Oct 2016, Markus Neteler wrote:
> 
>>> nsres:      1.00019858
>>> ewres:      1.00059954
>>
>> ^-- you have no-square pixels, is that on purpose? Of course that's
>> supported but just to reduce the amount of error if undesired.
> 
> Markus,
> 
>    Nope. That's the result of re-projecting from
> NAD_1983_HARN_StatePlane_Oregon_North_FIPS_3601_Feet_Intl (EPSG 2992) to
> NAD83(HARN) / Oregon North (EPSG 2838). I saw the discrepancy but assumed
> GRASS knew what it was doing.
> 
>    I can see how that could cause the problem.

I've got the data offline, and tested locally

findings with the coordinates taken from the thread:

r.watershed elevation=outraster at data drainage=draindir                          
r.water.outlet input=draindir at data output=basin
coordinates=2295821.27858,175258.094514

to see the r.water.outlet results, just do

r.to.vect input=basin output=vbasin

the result is just 1 pixel, as already earlier mentioned in the thread,
because the coordinates=2295821.27858,175258.094514 aren't a outlet point.

easy to check by e.g.

r.stream.extract elevation=outraster at data accumulation=accum at data
threshold=10 d8cut=1000000000000 stream_raster=runiqe stream_vector=vunique

then v.in.ascii 2295821.27858,175258.094514, and overlay the extracted
streams and the v.in.ascii-vector

randomly tested

r.water.outlet --verbose input=draindir at data output=basin2
2295824.16407,175258.754074 (which is on the stream network by
r.stream.extract); see screenshot  check.png
<http://osgeo-org.1560.x6.nabble.com/file/n5289100/check.png>  ru

the solution may be, find a outlet point which is on the stream network
which is appropriate for your analysis and then run r.water.outlet.










-----
best regards
Helmut
--
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