[GRASS-dev] r.watershed2 with MFD

[Markus Metz]

I have SVN commit access for grass-addons, is this also valid for grass7?

BTW my nightmare is to screw up the svn history that's why I hesitate to
submit directly to grass7 (or grass64).


Helena Mitasova wrote:
> Markus,
>
> at this point, as you suggest, the best would be to work on this in
> grass7 - do you have SVN commit access?
>
> Helena
>
>
> On Dec 5, 2008, at 3:02 PM, Markus Metz wrote:
>
>>
>> Dylan Beaudette wrote:
>>> On Fri, Dec 5, 2008 at 1:55 AM, Markus Metz <markus_metz at gmx.de> wrote:
>>>
>>>> I took the request for MFD support in r.watershed by Helena and
>>>> Dylan to
>>>> heart and implemented it, but still need a few more days to clean
>>>> up the
>>>> code, then I want to submit it as r.watershed2.mfd to grass-addons.
>>>>
>>>>
>>> Is there any way to
>>> cleanly merge this with the existing r.watershed code in SVN so that
>>> we can test it?
>>>
>> Also considering Michael's remarks, I suggets that I then not submit to
>> grass-addons, but to grass 7. Not to grass-6.4.x, because this code is
>> now more experimental and documentation still needs to be written.
>> The MFD algorithm seems to be robust and produces the expected results
>> with nice differences according to the convergence factor, but the other
>> outputs are different and I don't know yet if this is ok and desired
>> or not.
>> The basins and half-basins are different, less so for coarser
>> resolution, rather disastrous with MFD for the 1m LIDAR DEM in the North
>> Carolina dataset. It seems that such a DEM should be processed with
>> coarser resolution to obtain basins and half-basins that make sense,
>> apparently both for SFD and MFD, but these a just first impressions.
>
> You may be using a threshold that is too small.
>>
>> Slope length (LS for USLE) and slope steepness (S for USLE) are about
>> 99.9% identical between SFD and MFD with the DEM <elevation> in the
>> North Carolina dataset. Streams are again different, i.e. MFD streams
>> need to be thinned then they are very similar to SFD, but MFD streams
>> make sense.
>> Once I have added MFD to segmented mode too and updated the
>> documentation, the module is ready to be submitted and scrutinised by
>> others.
>>
>> This is no easy feat to modify r.watershed, I want to make sure the old
>> behaviour is preserved when adding new functionality and I need some
>> more time before submitting. I don't like to submit code with bugs...
>>
>> Markus Metz
>>
>>
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>