merging TM and panchromatic

[ALOBO]

"""> Can anybody tell me how to  merge TM Image(30 m res) and Spot Panchromatic
> image(10m res) using grass to produce a composite image ?  Thank you very
> much in advance .
>
> Prakash Basnyat

I'd say: produce a color image from the TM data at 30 m res, then use d.his
at 10 m res to `shade' your color image with the SPOT panchromatyic image.
You do this by telling d.his the TM data are the `hue' layer and the SPOT
data are the `intensity' layer; there's no `saturation' layer here.

P. Martijn van Leusen """

Yhis is correct as far you only need the merging for display purposes. If
you actually want to enhance the spatial resolution with th SPOT panchromatic
there are 2 methods that I know give good results:
1. (i) Perform a PCA on the TM image; (ii) substitute PC1 by the Spot Panchromatic;
(iii) Perform the inverse PCA.
2. Use cokriging to interpolate the TM with the SPOT. This can be done for 
each TM band, or, better, only with PC1 and then perform the inverse PCA.
Agus