[GRASS-user] i.maxlik can't read signature from i.class

[Cesar Augusto Ramírez Franco]

Hello Nikos,

2013/11/27 Nikos Alexandris <nik at nikosalexandris.net>

> Cesar Augusto Ramírez Franco wrote:
>
> > Hello everyone,
>
> Hello,
>
>
> > I've been trying to do a supervised classification from landsat8 imagery
> > using i.class and then i.maxlik, but I'm getting an error when running
> > i.maxlik saying it can't read the signature file.
>
> Just to double-check: verify that your "classes" don't overlay any NULL
> cells.
> It might be completely irrelevant, I have, though, blurry memories of this
> being a blocker actually (with i.smap at least).


​There are no NULL cells on my classes, neither on my Landsat 8 images or
the Landsat 7 in the North Carolina dataset

> I tested my procedure on the NC sample dataset and I'm getting the same
> > error, I'm using Grass 6.4.2 on Debian Wheezy, installed from the debian
> > repo. Here's the command set:
>
> > #Display RGB enhanced map
> > i.landsat.rgb blue=lsat7_2000_10 green=lsat7_2000_20 red=lsat7_2000_30
> > d.rgb blue=lsat7_2000_10 green=lsat7_2000_20 red=lsat7_2000_30
>
> > #"Real color" map
> > r.composite red=lsat7_2000_30 green=lsat7_2000_20 blue=lsat7_2000_10
> > output=lsat7_2000_RGB
>
> > #Group images to process
> > i.group group=lsat7_2000_RGB subgroup=lsat7_2000_RGB
> > input=lsat7_2000_10,lsat7_2000_20,lsat7_2000_30
>
> > #Unsupervised classification
> > i.cluster group=lsat7_2000_RGB subgroup=lsat7_2000_RGB sigfile=clustlsat7
> > classes=20 report=rep_clust_lsat7.txt
>
> (I have never tried to feed a group that uses a single composite. I'll try
> it
> out.)
>

The composite is for the supervised clasification, the group and subgroup
are made with the 3 RGB bands (1,2,3 in Landsat7 or 2,3,4 in Landsat8)​

> i.maxlik group=lsat7_2000_RGB subgroup=lsat7_2000_RGB sigfile=clustlsat7
> >  class=lsat7_classes reject=lsat7_classes_rej
>
> Does the unsupervised classification work?  i.cluster requires at least two
> input raster maps. And, honestly, I have never tried it the way you did,
> i.e.
> by using a composite map.  Also, r.composite will use by default "32
> levels"
> whicih means that you loose important info for the subsequent
> classification,
> if I am not wrong.


​The supervised classification does work, i.cluster generates a signature
file and i.maxlik success to create the classes raster map

> #Supervised classification
> > i.class map=lsat7_2000_RGB group=lsat7_2000_RGB subgroup=lsat7_2000_RGB
> > outsig=classlsat7
> > i.maxlik group=lsat7_2000_RGB subgroup=lsat7_2000_RGB sigfile=classlsat7
> > class=lsat7_class_sup
>
> > Here I get the error in which i.maxlik can't read the signature file
> > created by i.class (classlsat7) but read the one created by i.cluster
> > flawlessly
> >
> > This is what I'm selecting on the i.class monitor, I named it vegetation:
> > [image: Imagen integrada 1]
>
> Only on class?  Can you try with more please?
>

Yes, the error I'm getting is only with the i.class module

I'm doing some tests creating a test vector​​ with my classes as areas,
then converting it to raster with v.to.rast, and then using that raster to
generate statistics for i.smap with i.gensigset

I don't know if I'm not using the i.class module the right way or if it's
broken

> And the contents of the classlsat7 signature file are the following:
> >
> > #
> >
> > #vegetation
> >
> > 166
> > ​
> > Am I doing something wrong or is it some kind of bug?
>
> Greets, Nikos
>

​Thank you very much​

-- 
*César Augusto Ramírez Franco*
Laboratorio de Sistemas Complejos Naturales
Escuela de Geociencias
Facultad de Ciencias
Universidad Nacional de Colombia - Sede Medellín
Teléfono: (57-4) 430 9369 - 301 389 5607
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