How to mosaic TM images in GRASS?

[Simon Cox]

Peter

I would suggest rectifying before patching, since the two scenes may
have different distortions which should be removed first so that
the overlap will co-register.  Rectifying is straightforward if you
use i.rectify.  You import the data as an x-y set initially, then
run i.group to gather the different bands together so that they
are rectified as a group, run i.target to select the target (utm)
location, then run i.points to select the registration
points, then i.rectify to move the data from the x-y location to the
utm location.  After rectification, use r.patch for each of the bands.

I've never done this for imagery, only rasters, which were imported as
a single band image before rectification, but I think this sequence is
correct.

Good luck

Simon Cox
----
__________________________________________________________________
				Dr Simon Cox
         __  L				
      ,~'  L_|\            	Department of Earth Sciences       
   ,-'         \         	Monash University    
   (            \		Clayton  Vic  3168  Australia
   \    ___     /	
    L,~'   "\_x/		Phone +61 3 565 5762
              u   		Fax   +61 3 565 5062
				simon at cerberus.earth.monash.edu.au
__________________________________________________________________


----- End Included Message -----

Dear Sir:
I agree the procedure you have suggested. I have rectified and patched five Landsat MSS images for southeast Alabama. Each Landsat MSS image has four bands. I believe the rectification and patch will be easier for Landsat TM images. It's very difficult to rectify the Landsat MSS images. Anyway, It's over now.

John Wu