Hi, After implementing gain and bias correction and topographic correction, I get very low values for landsat data data for example range of values of band1:
GRASS 6.3.1svn (p112r056):~ > r.info lsat7_2000.toar.1 -r min=0.030303 max=0.372067 [Raster MASK present] GRASS 6.3.1svn (p112r056):~ > r.info tcor.lsat7_2000.toar.1 -r min=0.039443 max=0.442334 Running these range of values to an i.cluster reports very low separability: means and standard deviations for 3 bands means 0.00 0.00 0.00 stddev 0.06 0.00 0.00 initial means for each band class 1 -0.05 0.00 0.00 class 2 -0.05 0.00 0.00 class 3 -0.05 0.00 0.00 class 4 -0.05 0.00 0.00 class 5 -0.04 0.00 0.00 class 6 -0.04 0.00 0.00 class 7 -0.04 0.00 0.00 class 8 -0.04 0.00 0.00 class 9 -0.03 0.00 0.00 class 10 -0.03 0.00 0.00 class 11 -0.03 0.00 0.00 ... "More output here but mostly 0 value for means and stdev" ######## iteration 1 ########### 2 classes, 100.00% points stable class distribution 2161 7 ########## final results ############# 1 classes (convergence=100.0%) class separability matrix 1 1 0 class means/stddev for each band class 1 (2161) means 0.00 0.00 0.00 stddev 0.00 0.00 0.00 #################### CLASSES #################### 1 classes, 100.00% points stable ######## CLUSTER END (Mon Jun 16 15:12:59 2008) ######## I assume this is due to the very low range of values (0.0xxx) of the input images. Running r.rescale.eq to "stretch" the range of values doesn't also help. Any ideas on converting the radiance values to a range acceptable to i.cluster and i.maxlik? cheers, maning PS. Running i.landsat.rgb gives very good result to the output image (less topographic effects) but this just changes the color rules and not the actual values. -- |---------|----------------------------------------------------------| | __.-._ |"Ohhh. Great warrior. Wars not make one great." -Yoda | | '-._"7' |"Freedom is still the most radical idea of all" -N.Branden| | /'.-c |Linux registered user #402901, http://counter.li.org/ | | | /T |http://esambale.wikispaces.com| | _)_/LI |---------|----------------------------------------------------------| _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user