[GRASS-dev] i.segment gives different results in G72 and G73

[Markus Metz]

On Mon, Dec 5, 2016 at 1:46 PM, Martin Landa <landa.martin at gmail.com> wrote:
>
> Hi,
>
> 2016-12-05 9:09 GMT+01:00 Moritz Lennert <moritzlennert at posteo.net>:
> > What colleagues here have also noticed is that between the versions
(but I can't remember if it was 7.0 vs 7.3 or 7.2 vs 7.3) quite different
thresholds were needed to reach similar segmentation results. In 7.3
reasonable thresholds are often an order of magnitude lower, i.e. 0.001
instead of 0.01...
>
> this wasn't my case.

I am also getting very similar results with the same threshold. Can your
colleagues provide an example where such different thresholds need to be
used to obtain comparable results?

> I am getting slightly different results in G72
>
> i.segment complete. Number of segments created: 4367082
> (Sun Dec  4 09:42:19 2016) Command finished (3 min 36 sec)
>
> and G73
>
> i.segment complete. Number of segments created: 4359666
> (Mon Dec  5 13:45:41 2016) Command finished (4 min 44 sec)
>
> But not so much. Segmentation process is also a little bit slower in
> this case (and takes more iterations: 8->14). Ma

Strange. E.g. with ortho_2001_t792_1m from the NC dataset and a threshold
of 0.25, G72 needs 20 min 29 sec while G73 needs only 6 min 14 sec. The
speed gain of G73 is more prominent when there are large objects.

Markus M
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