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ropensci / MODIStsp

An "R" package for automatic download and preprocessing of MODIS Land Products Time Series
https://docs.ropensci.org/MODIStsp
GNU General Public License v3.0
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KNDVI (expression) - MODIStsp #233

Closed Olive-r closed 3 years ago

Olive-r commented 3 years ago

Hello,

Can the new KNDVI * be applied BY by using MODIStsp?

If yes, how should the expression be applied?

Thanks.

Oli

G. Camps‑Valls, M. Campos‑Taberner, Á. Moreno‑Martínez, S. Walther, G. Duveiller, A. Cescatti, M. D. Mahecha, J. Muñoz‑Marí, F. J. García‑Haro, L. Guanter, M. Jung, J. A. Gamon, M. Reichstein, S. W. Running, A unified vegetation index for quantifying the terrestrial biosphere. Sci. Adv. 7, eabc7447 (2021). doi: 10.1126/sciadv.abc7447

ranghetti commented 3 years ago

Hello, you can add it as new index: open the MODIStsp GUI with MODIStsp(), then click on the "Add New Spectral Index" button (bottom of the first sheet) and add the index related information: Screenshot_20210305_161050

ranghetti commented 3 years ago

Ps: please notice that I wrote the formula as an example, following the statement "A reasonable choice is taking the average value σ = 0.5(NIR + red)". Cange the formula accordingly to your needings.

Olive-r commented 3 years ago

Thank you very much Luigi!

I had several doubts to formulate the expression by using MODIStsp, and precisely one of them was the sigma parameter. The authors recommend σ=0.5, but the code illustrated as an example in the supplementary material shows σ=1. You are right. The authors go into more detail about sigma in the supplementary material: https://advances.sciencemag.org/content/suppl/2021/02/22/7.9.eabc7447.DC1/abc7447_SM.pdf

Thanks for everything. This R package is fantastic.

Oli