[GRASSLIST:3786] Re: image fusion

[Markus Neteler]

On Wed, May 29, 2002 at 12:20:28PM +0530, Anil Kumar Bhagat wrote:
> Dear Grass users, 
>                     Is it possible to fusion of two type of images , one
> having high spectral resolution and other having high spatial resolution . 
> for example  (LISS 3 and PAN ) .  Please suggest me .

Hi, you can perform
 - a IHS/RGB transformation (i.rgb.his, i.his.rgb)
     (first set region to low resolution channels, then i.rgb.his,
      then set region to high resolution channel, and transform back
      in the following way:
      For i.his.rgb use the previous channels "hue" and "saturation", but
      use, instead of the previously generated "intensity" the high
      resolution channel. The result are the fusioned RGB channels).
 - a Brovey transformation
     (here for SPOT, should be similar for LISS:
        g.region res=10
 	r.mapcalc "brov.red=   1. * spot.ms.3 / (spot.ms.1 + spot.ms.2\
                                        + spot.ms.3) * spot.p"
	r.mapcalc "brov.green= 1. * spot.ms.2 / (spot.ms.1 + spot.ms.2\
                                        + spot.ms.3) * spot.p"
	r.mapcalc "brov.blue= 1. * spot.ms.1 / (spot.ms.1 + spot.ms.2\
                                        + spot.ms.3) * spot.p"
	r.colors brov.red col=grey
	r.colors brov.green col=grey
	r.colors brov.blue col=grey
 
	#note the reversed r/g channels:
	d.rgb g=brov.red r=brov.green b=brov.blue
      )
....with existing GRASS tools.

There are many more fusion methods, but maybe you start with
above.

Best regards

 Markus

-- 
Markus Neteler

ITC-irst, Istituto per la Ricerca Scientifica e Tecnologica
     Project on Predictive Models for the Environment    
Via Sommarive, 18        -      38050 Povo (Trento), Italia
tel +39 0461 314 -520 (fax -591)          http://mpa.itc.it
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