[GRASS-user] FW: i.spec.unmix - scale results to 0-100%

[Stefan Blumentrath]

Oops, forgot to copy the list…

From: Stefan Blumentrath
Sent: mandag 6. november 2017 13.15
To: 'Žofie Cimburová' <zoficimburova at gmail.com>
Subject: RE: [GRASS-user] i.spec.unmix - scale results to 0-100%

My guess would be that you have to normalize the data for every layer in each pixel, like
r.mapcalc expression=”water_n= float (water-min(water, builtup, forest))/ float (max(water, builtup, forest)-min(water, builtup, forest))\
builtup _n= float (builtup-min(water, builtup, forest))/ float (max(water, builtup, forest)-min(water, builtup, forest))\
water_n=float(forest-min(water, builtup, forest))/ float (max(water, builtup, forest)-min(water, builtup, forest))”

Or something like that…

Cheers
Stefan

From: grass-user [mailto:grass-user-bounces at lists.osgeo.org] On Behalf Of Žofie Cimburová
Sent: mandag 6. november 2017 11.18
To: Markus Neteler <neteler at osgeo.org<mailto:neteler at osgeo.org>>
Cc: GRASS user list <grass-user at lists.osgeo.org<mailto:grass-user at lists.osgeo.org>>
Subject: Re: [GRASS-user] i.spec.unmix - scale results to 0-100%

Hi,
On Fri, Nov 3, 2017 at 5:06 PM, Markus Neteler <neteler at osgeo.org<mailto:neteler at osgeo.org>> wrote:
On Fri, Nov 3, 2017 at 11:10 AM, Žofie Cimburová
<zoficimburova at gmail.com<mailto:zoficimburova at gmail.com>> wrote:
> Hi,
> I am using i.spec.unmix for spectral unmixing of Sentinel-2 imagery. I
> define 6 endmembers and the results look pretty fine, but when I add the
> output maps up, they don't sum up to 100%, but rather anything from 23 till
> 67...
> I tried to linearly scale the output maps to 0-100% and then add them up,
> but this does not sum up to 100% either.
> In the manual there is a small comment "# todo: reclass to 0..100%".

There was a change for this but probably not catching the problem:

On Tue, Jul 4, 2017 at 10:53 PM,  <svn_grass at osgeo.org<mailto:svn_grass at osgeo.org>> wrote:
> Author: ychemin
> Date: 2017-07-04 13:53:58 -0700 (Tue, 04 Jul 2017)
> New Revision: 71240
>
> Modified:
>    grass-addons/grass7/imagery/i.spec.unmix/main.c
> Log:
> trying to rescale from 0-256 to 0-100, with according colour scheme



> How do I perform the reclassification manually?

Probably
https://grass.osgeo.org/grass72/manuals/r.rescale.html
but it would be better to get the Addon completed.

This does not solve my problem - the output maps are not scaled to 0-255. The ranges of my output maps are e.g. Map 1-water: 0-34, Map 2-builtup: 0-65, Map 3-forest:0-13, ....
I tried to r.rescale each map to 0-100, but they then don't sum up to 100 either. Is there probably different scaling for each output map? Or how else can I interpret the results if not in form of ratios?

Thanks,
Zofie

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