[GRASS-user] Derivation of Landsat 8 Tasseled Cap coefficients for certain scene in Grass

[Kozlova Maria]

Dear colleagues, 

Thank you for response.
a little bit later I will type the full procedure for derivation of TC coefficients.
PCA itself cannot be applied here as it is based only on statistical information of the image. TCT is physically based transformation and PCA is only the first step.
The main problem I see here is the 'soil line' which must be determined (manually or automatically) and PCA axes rotation to align 1st PCA component in accordance to the soil line.
Though I have to describe it in more details later...

-- 
Best regards,

Maria V. Kozlova

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10.06.2015, 10:38, "Moritz Lennert" <mlennert at club.worldonline.be>:
> On 09/06/15 23:42, Kozlova Maria wrote:
>
>>  Dear all,
>>  Asking for help in sudden difficult situation:
>>  I need to derive proper, 'personal', Tasseled Cap coefficients for some scenes of my study area.
>>  I know, such procedure can be done by Matlab, but unfortunately, my colleague who could do this have now some troubles and cannot help me at the moment.
>>
>>  I need to do this work but can use only Grass. So is it possible to derive my own TC coefficients for each scene using Grass? If so, which modules should I use?
>>  Is it possible to do image Tasseled cap transformation with these new coeficients?
>>  Am I right, that Grass module i.tasscap only provide TCT with use of standard TC coefficients (in the case of OLI images derived by M.H.A Baig et al, 2014)?
>
> Yes. BTW, the module is actually "just" a python script [1], so you
> easily modify the coefficients if you want to.
>
> Tassled cap coefficients are derived via principal component analysis +
> possibly some rotation. You can actually get pretty close by just doing
> your own PCA using i.pca. As Nikos said: it all depends on what you want
> to do.
>
> Moritz
>
> [1]
> https://trac.osgeo.org/grass/browser/grass/trunk/scripts/i.t…