Dear list,
I imported a georeferenced orthophoto (tif with tfw) with all bands (RGB) using r.in.gdal.
The result (3 raster layers red, green and blue) looks like very , what means that there is not much to recognize any more on the orthophoto.
Any suggestions how to enhance the of the orthophoto?
Regards
Christian
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On Wed, 2008-10-15 at 12:01 +0000, christian Brandt wrote:
Dear list,
I imported a georeferenced orthophoto (tif with tfw) with all bands (RGB) using r.in.gdal.
The result (3 raster layers red, green and blue) looks like very , what means that there is not much to recognize any more on the orthophoto.
Any suggestions how to enhance the of the orthophoto?
Regards
Christian
Hi Christian!
Splitting the colour orthophoto in three channes means that you are now
able to manipulate the 3 levels of this multi-dimensional "stack" of
information the way you want. You can for example use all 3 channels to
perform a classification or you can selectively use only 2 or 1! It
always depends upon what you want to do.
You can of course view the "normal" RGB image (with d.rgb where r=red
channel, g=green channel, b=clue channel). Now if viewing/visual
interpretation is your aim, you can create a composite (r.composite) and
use this as a single image for viewing (not for classifying).
About the colors you can either stretch all channels before creating the
composite or you might want to look in i.landsat.rgb (it's a very nice
auto-color-balancing tool).
FWIW, I think that GRASS is not well doing when it comes to pan/zoom an
image or visually cross-compare it with another. I prefer to open the
images with OpenEV (opening the raster maps from the /cellhd directory
or exporting them as tiffs).
Hope this helps, Nikos