[GRASSLIST:7026] Re: failure when running i.gensigset

Jachym Cepicky jachym.cepicky at centrum.cz
Mon Jun 6 09:15:35 EDT 2005

does r.stats+CLUSTER produce somehow "better" results, than i.gensigset?


On Mon, Jun 06, 2005 at 08:43:11AM -0400, Daniel Gavin wrote:
> Dear Knut,
> I have had correspondence with Charlie Bouman, the author of 
> i.gensigset, about this issue.  There is a problem with the code. As 
> I understand it, for certain large data sets, it can't solve the 
> fitting of the variance-covariance matrix.  i.gensigset is prone to 
> result in singular matrices..this is where I show my ignorance on 
> exactly how it works....but as the dimensionality of the data 
> increases there is a greater chance this will occur.  On Charlie's 
> website (http://dynamo.ecn.purdue.edu/~bouman/ ) is a new version, 
> called CLUSTER, which has an algorithm that detects and deals with 
> singularities.  You must compile this code on your computer (there is 
> a makefile; I am sure others on this list can recommend the best way 
> to compile if this is new to you). There is also a user's manual and 
> some example files.  I dump the data out of grass using r.stats -1n 
> input=grid1,grid2,grid3 output=cluster_input.txt
> where grid1, grid2, grid3  etc are the 'bands' in the imagery 
> subgroup that you wish to use.
> The above r.stats command must be run for each class (I use a mask to 
> subset the map into classes).  CLUSTER takes the above text file and 
> an information file (stating the file names for each class.) as 
> input.  The file created by CLUSTER can be put into the correct 
> folder (in the proper group, subgroup, sigset folder) and be used 
> with i.smap.  You will need to edit this file, however.  It requires 
> different numbers at the end of the lines that start with
> classnum:
> Otherwise i.smap will classify everything as the same class.  You 
> also need to be sure that the file named REF in the subgroup lists 
> your rasters in the same order they are used in CLUSTER.
> Charlie Bouman also said he has made minor improvements to i.smap 
> (called smap in the version on his website), but the changes to 
> i.gensigset were substantial.  I think it would be nice if someone 
> who knows how can update i.gensigset using CLUSTER, assuming Dr. 
> Bouman agrees.
> Cheers,
> Dan
> At 1:45 PM +0200 6/6/05, knut.langeland at nina.no wrote:
> >Dear list
> >
> >I'm doing some analysis of orthophotos with i.gensigset and i.smap, 
> >but suddenly when running i.gensigset i get this:
> >
> >GRASS 6.1.cvs (ortho35):~ > i.gensigset trainingmap=2616trening 
> >group=2616 subgroup=2616 signature=2616sign1  
> >Finding training classes ... 100%
> >ERROR: G_calloc: out of memory
> >GRASS 6.1.cvs (ortho35):~ >
> >
> >I'm running it on cygwin with 6.0.0., and I have tried to reinstall 
> >both cygwin and GRASS 3 times but the same thing happens again. 
> >In my prosesses window of the windows task manager the i.gensigset 
> >appears two times counting different amounts of memory when runnig 
> >the module. I'm in short of time so if anyone has an answer I'll 
> >be very happy!!!!
> >
> >Knut
> >
> ><mailto:d at nina.no>
> >
> -- 
> Dan Gavin
> Research Associate
> University of Vermont
> Botany and Agricultural Biochemistry
> 120B Marsh Life Science
> 109 Carrigan Dr.
> Burlington, VT 05405-0086
> 802.656.0297

Jachym Cepicky
e-mail: jachym.cepicky at centrum.cz
URL: http://les-ejk.cz
GPG: http://les-ejk.cz/gnupg_public_key/

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