[GRASS-user] How to perform Layer reduction for hyperspectral image cube?

[Nikos Alexandris]

Asefa Areda wrote:
> Dear All:

Hello Asefa,

> I want to reduce layers from NOVASOL hyperspectral image cube which has 140
> bands/layers.

> 1) How can I perform layer reduction

I have no experience with Hyperspectral imagery. But PCA should be a valuable 
option to consider. Have a look at the manual

<http://grass.osgeo.org/grass64/manuals/i.pca.html>

and some examples in a GRASS-Wiki page

<http://grasswiki.osgeo.org/wiki/Principal_Components_Analysis#Using_i.pca>

> 2) If I want use* i.atcorr *should I process only a single layer  at a time?

You "can" only process one layer per run.

> 3) if 2) is not how do I process all the layers in one go (the txt? 4) Is
> there any means to include a new sensor outside what is lited in the
> ''predefined sensor'' e.g., 64: 4th band of ETM+ Landsat 7

a) You need to script it in order to get it run for multiple "layers" in one 
go.  If you work under Linux, I can send you a Bash shell linux script (off-
list) I have used to run i.atcorr for some Landsat scenes. It'll sure need 
some hand-crafting as there are some hardcoded stuff.

Maybe some-one has already a "clean" solution on that.

b) For "adding new band filters", have a look at: 
<http://trac.osgeo.org/grass/browser/grass/trunk/imagery/i.atcorr/README>

Regards, Nikos