i.pca

[imager at ccwf.cc.utexas.edu]

I'd like to make a correction to my last posting (question 2). I can see
how I could approximate the first principal component for 4 input 
images (i.e. ((band1+band2+band3+band4)/4))) but I'm unsure how to
approximate the three remaining component images. Does any one know
how to do this?

Thanks again in anticipation of any help,

Tony Gale.

 of 
   GRASS to the RISC 6000 platform?

2) If the above "i.pca" problem I'm having is platform related is there an
   alternative approach that would enable me to remove band correlation
   (I know how I could do so using 2 bands but not 3 or more) - maybe using
   "r.mapcalc"?

3) I was recently using "i.target,i.points and i.rectify" to reference a 
    previously (State Plane) rectified SPOT image in row, col to State
    Plane coordinates. I would like to know if the i.rectify algorithm
    uses a third order polynomial to rectify the input images or whether
    it matches the most appropriate transformation equation to the inputted
    control point coordinates?


Thanks in advance for any help.

Tony Gale