[GRASS-user] Ratioing and pan-sharpening

Knut Arne Bjørndal bob+osm at cakebox.net
Sun Jun 21 11:43:49 EDT 2009


I'm trying to create a base layer for a topo map using a DEM and
landsat data.

To make sure everything isn't simply a smear of colors I use ratioing
of the landsat bands so that I can draw with a couple of different
colors. I currently use 4-3/4+3 (ndvi) and 5-6/5+6.

Now I would like to pan-sharpen to improve the resolution of the
finished product, and I'm wondering what the best way to do this is.

First: Do I pan-sharpen the original band data before ratioing, or do
I sharpen the ratio output somehow?

Second: What's the best way to pan-sharpen this? Most examples I could
find talked a lot about getting a natural-looking rgb image, which
isn't what I want.

I tried i.fusion.brovey, and sharpened bands 3, 4 and 5 and then tried
ratioing based on that but the output was very different (in a worse
way) than the normal NDVI.

Then I tried a receipe from "Open Source GIS" which translated the
image to HIS and back again with band 80 as intensity, this seems to
have helped the resolution of the 5/6 ratio, but not the 4/3. I did
the sharpening using red=band30 green=band40 blue=band50.

Oh, and is it possible to pan-sharpen band 6 data too?

PS: I'd appreciate copies of replies directly to me in addition to to
the list since I often don't have the time to read the list.

Knut Arne Bjørndal
aka Bob Kåre
bob+osm at cakebox.net
bobkare at irc
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