[GRASS-user] i.atcorr range and rescale parameters for Sentinel 2 images

[Markus Metz]

On Thu, Feb 8, 2018 at 8:54 PM, roberta fagandini <robifagandini at hotmail.it>
wrote:
>
> Hi all,
>
> I'm testing i.atcorr (grass 7.4) with Sentinel 2A images and i have some
trouble defining the right values for range and rescale parameters. I read
in other posts and lists that the suggested value for both range and
rescale is '0,10000' while in other posts someone else suggests to use min
and max values (from r.info) for range and '1,10000' or '0, 10000' for
rescale.
>
> It's not clear to me the right meaning of these parameters and thus the
most correct values to be used.
>
> Can anyone better explain me the meaning of these two parameters?

In Sentinel2, the value 0 means nodata, therefore the range must start with
1. The QUANTIFICATION_VALUE from the metadata (now 10000, previously 1000)
should be used as upper limit for range. Thus try range=1,10000
rescale=1,10000.

Markus M
>
> I tested all the values suggested in other posts but I can't understand
what they exactly do.
>
>
> Thank you in advance for your help!
>
>
> Roberta
>
>
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