[GRASSLIST:182] imagery classification tools for classification of terrian types

[Dylan Beaudette]

Hi everyone,

Attempting to do some simple geomorphologic classification based on parameters 
calculated from a DEM. 

I have tried a couple permutations of i.cluster i.gensig, and i.maxlik without 
success here are the commands that I used in my tests:

#1. training data based classification

i.group group=terrain subgroup=terrain 
input=slope_n,er9,profc,maxic,minic,longc

r.digit  --->terrain.train

i.gensig trainingmap=terrain.train group=terrain subgroup=terrain 
signaturefile=terrain.sig

#results in:
Finding training classes ...
 100%
3 classes.
Calculating class means ...
 100%
Calculating class covariance matrices...
 100%
Signature [1] not invertible.
Signature [2] not invertible.
Signature [3] not invertible.
Writing signature file [terrain.sig]

#i.maxlik dies with:
ERROR: Can't read signature file [terrain.sig].


2. unsupervised classification:
i.cluster group=terrain subgroup=terrain sigfile=terrain.sig classes=5

#results in:
Iteration 1: % Convergence: 100.00 (0s elapsed, 0s left)

i.maxlik group=terrain subgroup=terrain sigfile=terrain.sig 
class=terrain.class

#results in a map with all cells set to 1

I am using GRASS6.1-CVS and all of my input maps are FCELL or DCELL .... could 
this be the cause of my problems?


As a side note, this little adventure was started after reading a past paper 
by Roger Bivand on the use of R for a simple cluster-based approach to 
classifying terrain [1]. In his paper he goes over the aspects of getting 
data to move between GRASS and R, leaving the interpretation of the results 
to a geomorphologist. The R-approach seemed ideal, however I thought that I 
would try it with the GRASS classification commands first.

[1] Roger Bivand. Integrating GRASS 5.0 and R: GIS and modern statistics for 
data analysis. Internal Paper (?)
 
Thanks!



-- 
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341