[GRASS-user] i.maxlik problem

Markus Metz markus.metz.giswork at gmail.com
Tue Sep 18 12:33:56 PDT 2018

On Tue, Sep 18, 2018 at 3:38 PM Giuseppe Cillis <giucillis at gmail.com> wrote:
> Hi,
> I am in the first experiences with GRASS and I have a problem with the
i.maxlik module.
> I have to semi-automatically classify two orthophotos already
geo-referenced and rectified. As a first operation, I create a group and a
subgroup in which I put the two orthophotos. Next, I create a signature
with the i.cluster module (initial number of class = 5; iterations = 30;
percent convergence = 95%; minimum number of pixels = 5). But in the
resulting output there is a problem because the only classified part is the
overlap zone between the two orthophotos ... why?

you need to either classify each orthophoto separately (which is probably
not what you want) or first patch (the different bands of) the two
orthophotos together with r.patch, then run i.cluster + i.maxlik. When
patching the two orthophotos together, make sure the current region covers
both orthophotos, e.g.

g.region -p rast=orthophoto1,orthophoto2

Markus M

> I hope I was clear
> GC
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