[GRASS-user] Using i.atcorr on SPOT4 and SPOT5 imagery

[Markus Neteler]

On Wed, Jul 18, 2012 at 1:02 AM, Daniel Victoria
<daniel.victoria at gmail.com> wrote:
> From what I recall, i.atcorr was based off a fortran code writen by
...

Fortran 6S was written by Vermote/NASA (http://6s.ltdri.org).
This code was then rewritten by Christo Zietsman in South Africa to C
and updated by various developers.

> That original Fortran program expects the input
> images to be 8 bit and produces another 8bit image as a result. I
> believe that's why the grass i.atcorr has both the iscl and oscl
> options.
>
> In my opinion, these input and output scaling parameters confuses
> things a little. I'm not sure how the command works internally and if
> these parameters are needed but, I have a feeling they are necessary
> if we work with images with more than 8 bits.

A user would likely prefer that the scaling be done automatically...
Seems we have to study the source code...

Markus