[GRASS-dev] On i.histo.match (Re: On (Landsat) imagery naming patterns)

[Markus Metz]

On Wed, Feb 20, 2013 at 3:27 PM, Nikos Alexandris
<nik at nikosalexandris.net> wrote:
> On Wednesday 20 of February 2013 13:31:07 Nikos Alexandris wrote:
>> Greetings to the dev-list.
>
>> I successfully tested <i.histo.match>, by feeding it with 12 Landsat scenes
>> (working on identical bands, different Path/Row tiles) in one go.  It works
>> and I really enjoy it.
>
> Could it be that histo-matching works nicely only on 0-255 ranges but doesn't
> play nice in ranges 0-1.0? Integers only?

Yes, integers only. The i.histo.match script forces input raster
values to integers. But it might not be restricted to the 0-255 range.

>
> For example, when feeding images ranging from 0-1.0 (all Landsat bands 3) with
> the optional parameter "max=1", many of the histo-matched images are "flatten"
> to 1.
>
> I will try to "recode" 0-1.0 images to 0-255 and repeat the histo-matching
> process.

For rescaling to 0-1000, you could try something like

r.mapcalc "bandX_int = round(1000 * bandX)"

HTH,

Markus M

>
> Best, Nikos
>
>
>
>
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