[GRASS-user] pansharp fusion of ikonos image

Jonathan Greenberg jgreenberg at arc.nasa.gov
Mon Feb 26 16:02:17 EST 2007

Just as a heads up, most pansharpening algorithms introduce false spectral
information into the mix -- you might want to look into principle components
pansharpening algorithms, which tend to preserve the spectral values better
than the other commonly used ones...


The first hit is the paper that describes this (Welch and Ehlers, 1987)

The basic concept is you rotate a resampled "high resolution" multispectral
data (I think a nearest neighbor resample to match the high res resolution
is sufficient) into PCA space, the first PCA axis tends to be the albedo
band (which is the assumption for this analysis).  The high resolution pan
band is then substituted in to the PCA stack, replacing the first PCA axis
band, and then rotated back into spectral space.

I used this pansharpened data as the basis for several published papers
using IKONOS imagery, and it works very nicely (I used ENVI's implementation
of the algorithm)


On 2/26/07 12:48 PM, "Markus Neteler" <neteler at itc.it> wrote:

> Hi Massimo,
> please have a look at
> http://grass.itc.it/grass63/manuals/html63_user/imageryintro.html
> -> Image fusion
> or 
> g.manual imageryintro
> -> Image fusion
> I agree that it is minimalistic, please suggest how to improve the text
> (text snippets welcome!).
> So, yes, you have at least two possibilites besides r.mapcalc.
> Markus
> Massimo Di Stefano wrote:
>> Hi,
>> have you any suggestion on how can i do a ikonos "pansharp fusion"
>> using grass ?
>> there isn't a command that already done this things,
>> is possible to use an r.mapcalc expression to do it ? have you
>> experience about ?
>> thanks for any help!
>> Massimo.
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Jonathan A. Greenberg, PhD
Postdoctoral Scholar
Center for Spatial Technologies and Remote Sensing (CSTARS)
University of California, Davis
One Shields Avenue
The Barn, Room 250N
Davis, CA 95616
Cell: 415-794-5043
AIM: jgrn307
MSN: jgrn307 at hotmail.com

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