Hi Augusto,
In GRASS-6.4.3, i.class only works on 8bit images. Since the Landsat 8
products are
12bit data, proper signature files cannot be produced by i.class.
You could try rescaling data to 8bit and see if i.class and i.maxlik works.
Best
Venka
P.S. I hope i.class will be support 12, 16bit images in future.
On 2013/11/27 0:47, Cesar Augusto Ramírez Franco wrote:
Hello everyone,
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.
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.maxlik group=lsat7_2000_RGB subgroup=lsat7_2000_RGB sigfile=clustlsat7
class=lsat7_classes reject=lsat7_classes_rej
#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]
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?
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