[GRASS-user] Re: how to only fill small sinks with r.fill.dir

[Bryan Keith]

Great ideas, thank you. I did something like this:

r.fill.dir input=wl200310_krig_g elevation=wl200310_fill_g
direction=wl200310_dir_g
r.mapcalc wl200310diff_g=wl200310_fill_g - wl200310_krig_g

r.mapcalc wl200310diffsel_g = if("wl200310diff_g > 5.0", 0, wl200310diff_g)
r.mapcalc wl200310sel_g = wl200310diffsel_g + wl200310_krig_g
r.fill.dir input=wl200310sel_g elevation=wl200310sel_fill_g
direction=wl200310sel_dir_g

r.flow elevin=wl200310sel_fill_g flout=test_ln

I think my problem is now with r.flow.  I would like to see flows
continue through the filled sink and out the other end (as if it were
a lake), but that doesn't happen.  I don't think it can happen with
r.flow because r.flow encounters a flat area.

Not sure what to try next.  This was a problem even before messing
around with the sink tolerance.

Bryan

On Tue, Apr 26, 2011 at 10:31, Saber <razmjooeis at faunalia.co.uk> wrote:
> Sorry...I thought the sinks are as null values.
> Ignore my previous email.
> I can't think of anything apart from improving your DEM to get rid of the
> artifacts.
> One way will be to get the initial result from the r.fill.dir. Identify
> the areas where the depth is more than say 10 metre (r.nulls
> map=initial_result setnull 0-9.99)
>
> You can then add the new depth raster to the DEM to create the "filled
> hole". (first r.mask to match initial_result and then r.mapcalc
> filled_holes=initial_result+DEM)
> Then remove the mast and r.patch
> r.patch input=filled_holes,DEM output=patched_DEM
>
> You can then use the patched_DEM for r.fill.dir
>
> Hope that helps.
>
>
>
>> Hmmm, I'm not following all your steps, but I don't want to manually
>> identify valid sinks vs. invalid sinks.  I have quite a lot of
>> surfaces to process, and I'm happy to fill all sinks except those
>> deeper than 10m.
>>
>> On Tue, Apr 26, 2011 at 10:04, Saber <razmjooeis at faunalia.co.uk> wrote:
>>> Here is a (not a very quick) solution I can think of:
>>>
>>> 1- Create an inverse mask
>>> 2- convert the mask to vector (r.to.vect)
>>> 3- clean the vector file to get rid of the areas not required (v.clean)
>>> 4- convert the vector back to raster (v.to.rast)
>>> 5- Use the new raster as a mask for filling holes (probably you need
>>> step
>>> 4.5 to slightly buffer the raster)
>>>
>>> Hope that helps
>>>
>>>
>>>> Any ideas on this?
>>>>
>>>> Bryan
>>>>
>>>> On Mon, Apr 18, 2011 at 14:49, Bryan Keith <bkeith at itascadenver.com>
>>>> wrote:
>>>>> Hello,
>>>>>
>>>>> Is there a way to only fill sinks in a DEM if they are smaller than a
>>>>> certain tolerance?  I have a couple areas of internal drainage that
>>>>> really are correct (and quite large), and I have a quite few small
>>>>> sinks that are incorrect and artifacts of the interpolation.  Any
>>>>> ideas how to this?  r.fill.dir attempt to fill all the sinks.
>>>>>
>>>>> I'm trying to improve the results from r.flow  Too many tracks end in
>>>>> small holes where I'd like them to continue downstream.  Thanks.
>>>>>
>>>>> Bryan
>>>>>
>>>> _______________________________________________
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>>>>
>>>
>>>
>>>
>>
>
>
>