[GRASS-dev] Re: [GRASS-user] v.clean tool=prune - 'thresh' interpreted wrong?

Moritz Lennert mlennert at club.worldonline.be
Tue Oct 3 09:13:39 EDT 2006

Maciej Sieczka wrote:
> Markus Neteler wrote:
>> On Tue, Oct 03, 2006 at 02:23:56PM +0200, Moritz Lennert wrote:
>>> I would guess that the prune tool prunes all 
>>> "unneccessary" nodes on a straight line, i.e. any node which is not 
>>> necessary to define the line, and this whatever the threshold.
>>> The threshold only applies in cases of change of direction (i.e. angles).
>>> Just another example of the need for much more documentation for 
>>> v.clean, including example diagrams like the one for the rmsa tool.
>> Fully agreed...
> Markus,
> Agreed regarding what?

I think Markus responded to my remark on lack of documentation.

> Moritz just supposes but he is not sure. And if you look into my
> original email you'll that he's wrong:
> 1. a *straight* line, consisted of 4 vertices, at regular intervals of
>    10
> 2. thresh>0.03 prunes all vertices (besides the nodes of course)
> 3. thresh<=0.03 prunes none
> Then Moritz's idea is wrong.
> And I need to know exactly how the thresh in prune works, as I'm using
> it for my work. The result will be a script that I'm going to publish.
> Please - if anybody knows, tell me. I'd love to update the manual
> accordingly.



There is an explanation of the algorithm at the beginning.


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