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

[Markus Neteler]

On Tue, Oct 03, 2006 at 02:56:18PM +0200, 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?

... regarding that more documentation is needed.
 
...
> 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.

Apparently it can be only reverse engineered (luckily it's FOSS).
I was not too happy with my attempts to use the prune algorithm,
I don't think that it works reasonable well.

But this is an old story:
http://grass.itc.it/pipermail/grassuser/1995-January/012655.html
http://grass.itc.it/pipermail/grassuser/2006-July/035373.html
http://grass.itc.it/pipermail/grassuser/2006-August/035529.html

The first mail indicates that the problem is known and wasn't
resolved so far. Time to switch to another algorithm :-)

Markus