[GRASSLIST:1829] inverse r.composite?

Ian Macmillan ian_macmillan at umail.ucsb.edu
Wed Nov 19 21:23:52 EST 2003

Hi all, sorry to pester the list recently, but the more I try new things (I love
GRASS), the more questions I have (not a bad thing).  I have been working on
using i.ortho.photo lately.  Got all the bugs worked out with that (see earlier

Now I have a color orthorectified air photo in a UTM projection.  I would like
to project this color raster into a lat-long location.  Problem is that r.proj
seems to mess with the colors, and the newly projected air photo in the lat
long location has screwy colors (like a color ramp).  I can't figure out how to
get around this.  When I imported the original photo into my xy location, it
came in as a single rgb raster (both with r.in.tiff, and r.in.gdal).  Going
through i.ortho.photo kept the colors the same in the UTM location.  However
now the colors are scewball in the lat-long location.  I figured a fix would be
to separate the color orthophoto into 3 bands (ortho_photo.r, ortho_photo.g,
ortho_photo.b), sort of like r.composite, but in reverse.  I could then r.proj
each of those into the lat-long location, and composite them later.  I can't
figure out how to do this though.  Any ideas?  Is there another approach?  A
search through the archives unfortunately didn't help too much.

Thanks a million,  Ian

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