Re: [GRASS-user] i.cluster not working in GRASS 7

[Ned Horning]

Nick and Daniel,

Thanks for the suggestions. I did manage to get it to run after playing 
with some of the variables. If I used the default values for "sample" 
and "min_size" it worked. Unfortunately the default values are less than 
ideal. I think the main problem is with the "sample" parameter. When I 
enter "sample=5,5" I assume that every fifth pixel from every fifth line 
is being sampled for use in calculating the cluster statistics. This is 
apparently too many samples for i.cluster to handle. If I use 
"sample=100,100" the program works as expected (more or less). I have a 
feeling that the sample array is not able to handle a large number of 
samples.


Thanks again,

Ned


On 02/18/2011 09:22 AM, Nick Jachowski wrote:
Also, make sure you mask any Nulls since that often seems to be the 
problem when i.cluster doesn't work as expected, especially if you are 
using landsat 7 slc-off imagery - although I've also experienced it 
with Landsat 4 and 5 imagery.


[Sent from a mobile device]

On Feb 18, 2011, at 4:38 PM, Nick Jachowski > wrote:



Hi Ned and Daniel,

I have run into this problem in the past, and I believe it may have 
to do with your convergence, min_size, and classes settings.  Try 
decreasing some of those and see if you don't get better results. 
 You can also try increasing your separation from 0.0 (the default) 
to 1.0 or 1.5.


Nick

On Fri, Feb 18, 2011 at 4:24 PM, daniel mcinerney 
mailto:daniel.o.mciner...@gmail.com>> 
wrote:


Hi Ned,

I have been using i.cluster in GRASS 7 on a 64-bit fedora server,
without any trouble.  However, I managed to replicate your problem
and create a single class output by setting the parameter
'sample=5,5' as you had done in your example. If I run i.cluster
without
that parameter, the signature file and classification output both
have the number of predefined classes.

Can you see if this helps with your data?

Regards,
Daniel.


On Thu, Feb 17, 2011 at 7:49 PM, Ned Horning mailto:horn...@amnh.org>> wrote:

Hi - I would like to do an unsupervised classification using
i.cluster from GRASS 7 on my Ubuntu 64-bit machine. When I
run i.cluster then i.maxlik on a Landsat image I only get one
output class, the entire image. Only one class appears in the
signature file so the problem is with the i.cluster step. I
tried running i.cluster on different images and always get
just one class.

Here is the command line I'm using:
i.cluster group=TM_r15c33@PERMANENT subgroup=AllBands
signaturefile=IsoDataSigs2 classes=20 sample=5,5
convergence=99.9 min_size=1

Is anyone able to get i.cluster to work properly? It would be
helpful to know if it's a user problem or a bug.

Thanks in advance to anyone who can help.

All the best,

Ned
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Re: [GRASS-user] i.cluster not working in GRASS 7

[Nick Jachowski]

Also, make sure you mask any Nulls since that often seems to be the problem 
when i.cluster doesn't work as expected, especially if you are using landsat 7 
slc-off imagery - although I've also experienced it with Landsat 4 and 5 
imagery. 

[Sent from a mobile device]

On Feb 18, 2011, at 4:38 PM, Nick Jachowski  wrote:

> Hi Ned and Daniel,
> 
> I have run into this problem in the past, and I believe it may have to do 
> with your convergence, min_size, and classes settings.  Try decreasing some 
> of those and see if you don't get better results.  You can also try 
> increasing your separation from 0.0 (the default) to 1.0 or 1.5.
> 
> Nick
> 
> On Fri, Feb 18, 2011 at 4:24 PM, daniel mcinerney 
>  wrote:
> Hi Ned,
> 
> I have been using i.cluster in GRASS 7 on a 64-bit fedora server,
> without any trouble.  However, I managed to replicate your problem
> and create a single class output by setting the parameter
> 'sample=5,5' as you had done in your example. If I run i.cluster without
> that parameter, the signature file and classification output both 
> have the number of predefined classes. 
> 
> Can you see if this helps with your data?
> 
> Regards,
> Daniel.
> 
> 
> On Thu, Feb 17, 2011 at 7:49 PM, Ned Horning  wrote:
> Hi - I would like to do an unsupervised classification using i.cluster from 
> GRASS 7 on my Ubuntu 64-bit machine. When I run i.cluster then i.maxlik on a 
> Landsat image I only get one output class, the entire image. Only one class 
> appears in the signature file so the problem is with the i.cluster step. I 
> tried running i.cluster on different images and always get just one class.
> 
> Here is the command line I'm using:
> i.cluster group=TM_r15c33@PERMANENT subgroup=AllBands 
> signaturefile=IsoDataSigs2 classes=20 sample=5,5 convergence=99.9 
> min_size=1
> 
> Is anyone able to get i.cluster to work properly? It would be helpful to know 
> if it's a user problem or a bug.
> 
> Thanks in advance to anyone who can help.
> 
> All the best,
> 
> Ned
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Re: [GRASS-user] i.cluster not working in GRASS 7

[Nick Jachowski]

Hi Ned and Daniel,

I have run into this problem in the past, and I believe it may have to do
with your convergence, min_size, and classes settings.  Try decreasing some
of those and see if you don't get better results.  You can also try
increasing your separation from 0.0 (the default) to 1.0 or 1.5.

Nick

On Fri, Feb 18, 2011 at 4:24 PM, daniel mcinerney <
daniel.o.mciner...@gmail.com> wrote:

> Hi Ned,
>
> I have been using i.cluster in GRASS 7 on a 64-bit fedora server,
> without any trouble.  However, I managed to replicate your problem
> and create a single class output by setting the parameter
> 'sample=5,5' as you had done in your example. If I run i.cluster without
> that parameter, the signature file and classification output both
> have the number of predefined classes.
>
> Can you see if this helps with your data?
>
> Regards,
> Daniel.
>
>
> On Thu, Feb 17, 2011 at 7:49 PM, Ned Horning  wrote:
>
>> Hi - I would like to do an unsupervised classification using i.cluster
>> from GRASS 7 on my Ubuntu 64-bit machine. When I run i.cluster then i.maxlik
>> on a Landsat image I only get one output class, the entire image. Only one
>> class appears in the signature file so the problem is with the i.cluster
>> step. I tried running i.cluster on different images and always get just one
>> class.
>>
>> Here is the command line I'm using:
>> i.cluster group=TM_r15c33@PERMANENT subgroup=AllBands
>> signaturefile=IsoDataSigs2 classes=20 sample=5,5 convergence=99.9
>> min_size=1
>>
>> Is anyone able to get i.cluster to work properly? It would be helpful to
>> know if it's a user problem or a bug.
>>
>> Thanks in advance to anyone who can help.
>>
>> All the best,
>>
>> Ned
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>> grass-user mailing list
>> grass-user@lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-user
>>
>
>
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Re: [GRASS-user] i.cluster not working in GRASS 7

[daniel mcinerney]

Hi Ned,

I have been using i.cluster in GRASS 7 on a 64-bit fedora server,
without any trouble.  However, I managed to replicate your problem
and create a single class output by setting the parameter
'sample=5,5' as you had done in your example. If I run i.cluster without
that parameter, the signature file and classification output both
have the number of predefined classes.

Can you see if this helps with your data?

Regards,
Daniel.

On Thu, Feb 17, 2011 at 7:49 PM, Ned Horning  wrote:

> Hi - I would like to do an unsupervised classification using i.cluster from
> GRASS 7 on my Ubuntu 64-bit machine. When I run i.cluster then i.maxlik on a
> Landsat image I only get one output class, the entire image. Only one class
> appears in the signature file so the problem is with the i.cluster step. I
> tried running i.cluster on different images and always get just one class.
>
> Here is the command line I'm using:
> i.cluster group=TM_r15c33@PERMANENT subgroup=AllBands
> signaturefile=IsoDataSigs2 classes=20 sample=5,5 convergence=99.9
> min_size=1
>
> Is anyone able to get i.cluster to work properly? It would be helpful to
> know if it's a user problem or a bug.
>
> Thanks in advance to anyone who can help.
>
> All the best,
>
> Ned
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> grass-user@lists.osgeo.org
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>
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