[GRASS-dev] i.segment: Invalid region id -1

Nikos Alexandris nik at nikosalexandris.net
Tue Dec 3 11:50:48 PST 2013

Nikos Alexandris wrote:
> > >> I've tested this with at least three different similar cases. All work
> > >> fine without the seed map! All fail with a seed map supplied. I guess,
> > >> the only real difference is time for the processes to complete, right?

> > > OK, I've just discovered that I mixed 8-bit (the Pan images) for the
> > > seed map and 16-bit (the Multi-Spectral images).  So, seed -> 8-bit,
> > > group to be segmented -> 16-bit. Does this play a role?
Markus Metz:
> > No, the seed map must be integer (not more than 32 bit int), that's
> > the only limitation. The data to be segmented can be anything, integer
> > and/or floating point.

> Good to know.

I guess this is because the segments are only "counted" then.

> > But it does not make sense to use a pan band as seeds when segmenting
> > the other bands. Seeds are typically the result of a previous run of
> > i.segment or the result of a previous classification of the same data.

> Then I have inserted a small mistake in my tests/workflow. Wanted to drive
> "finer objects" (from Pan) in bigger ones (based on MS). Will adjust.

So, no problem here. All fixed. And, in most of the segmentations so far, 
indeed, I used pan only (frist segmentation, then seeding a second) and fed 
the derived objects with descriptive stats.

i.segment is a real working tool. It's awesome.


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