i.composite question

nick%ikaros at harvard.harvard.edu nick%ikaros at harvard.harvard.edu
Mon Jun 22 14:30:16 EDT 1992

I am a new user to GRASS and have a couple questions:

1) I've been having problems making a composite image from three
Landsat MSS bands. I use i.composite, and specify the three 
data bands. The program seems to run normally and produces a file
which looks almost normal, but it has too few colors or data values: 
it seems that similar values are being clumped together so that the
resulting image has only a dozen or so different values/colors. The
problem isn't with the monitor -- a histogram of the compostite
image shows just a series of spikes, not a smooth curve.  

2) Is there a way to rectify MSS and other imagery directly into a 
lat-long coordinate system? I can't get i.points to accept 
lat-long coordinates when I point to a pixel; it will only 
take UTM or other x,y coordinates. I could rectify first 
into a UTM database and then rectify that into a lat-long but that
seems unnecessarily roundabout. 

I would very much appreciate any help people could offer. Thanks in
advance --

Nick Cahill
Perseus Project
nick at ikaros.harvard.edu

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