Hei,
Before investing time in getting r.terraflow to work on larger regions I
actually tried r.fill.dir.
The problem is that the results are significantly different and those of
r.terraflow and r.hydrodem (where no breaching is performed) are more suitable
for my needs. Here, r.terraflow fills most, r.fill.dir least and r.hydrodem
inbetween.
Here a little comparison based on NC data:
g.extension extension=r.hydrodem operation=add
g.region -p raster=elevation
r.fill.dir --overwrite --verbose input=elevation
output=elevation_fill_dir_depressionless direction=elevation_fill_dir_direction
areas=elevation_fill_dir_pas
r.hydrodem -a --overwrite input=elevation memory=5000
output=elevation_hydrodem_depressionless
r.terraflow --overwrite --verbose elevation=elevation
filled=elevation_terraflow_depressionless memory=5000
for m in terraflow fill_dir hydrodem
do
r.mapcalc --o
expression="${m}_effect=if((elevation_${m}_depressionless-elevation)>0,elevation_${m}_depressionless-elevation,null())"
done
r.univar map="terraflow_effect"
total null and non-null cells: 2025000
total null cells: 1901290
Of the non-null cells:
--
n: 123710
minimum: 7.62939e-06
maximum: 12.5168
range: 12.5168
mean: 1.49711
mean of absolute values: 1.49711
standard deviation: 1.97871
variance: 3.91528
variation coefficient: 132.169 %
sum: 185206.976940155
r.univar map="fill_dir_effect"
total null and non-null cells: 2025000
total null cells: 1964852
Of the non-null cells:
--
n: 60148
minimum: 7.62939e-06
maximum: 10.9003
range: 10.9003
mean: 0.499953
mean of absolute values: 0.499953
standard deviation: 0.939429
variance: 0.882526
variation coefficient: 187.903 %
sum: 30071.1971092224
r.univar map="hydrodem_effect"
total null and non-null cells: 2025000
total null cells: 1020396
Of the non-null cells:
--
n: 1004604
minimum: 3.8147e-06
maximum: 4.74686
range: 4.74685
mean: 0.00587574
mean of absolute values: 0.00587574
standard deviation: 0.08715
variance: 0.00759513
variation coefficient: 1483.22 %
sum: 5902.79515457153
Cheers
Stefan
Fra: Markus Metz
Sendt: fredag 14. juni 2019 14.25
Til: Stefan Blumentrath
Kopi: grass-dev@lists.osgeo.org
Emne: Re: [GRASS-dev] r.terraflow vs. r.hydrodem
On Fri, Jun 14, 2019 at 1:23 PM Stefan Blumentrath
mailto:stefan.blumentr...@nina.no>> wrote:
>
> Hi,
>
> While trying to make r.terraflow work with larger regions, I was wondering if
> it would be doable to add a flag to r.hydrodem that forces the module to
> perform only sink filling and no breaching / carving?
>
> Sink filling is the function I need from r.terraflow but if it would be an
> option to add this function to r.hydrodem, that would be fine as well of
> course...
what about r.fill.dir? It should work as is with larger regions.
Markus M
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