Issuess with Vegetation Radiometric Indices / Soil Radiometric Indices


lately I’ve calculated the MCARI, BI and CI Indices using the MCARI Processor, BI Processor and the CI Processor in SNAP. I noticed some issues when checking the help section:

1. When opening the MCARI Help it says:

" The MCARI results from the following equation:

MCARI = ((red_factor2 * red2 - red_factor1 * red1) - 0.2 * (red_factor2 * red2 - green_factor * green)) * (red_factor2 * red2 / red_factor1 * red1)

For Sentinel-2 the formula is:

[(B5 - B4) - 0.2 * (B5 - B3)] * (B5 - B4) , where (Central wavelength/Bandwidth): B5 = 705 nm (15 nm), B4 = 665 nm (30 nm), B3 = 560 nm (35 nm)"

In the MCARI equation, the last part is (red_factor2 * red2 / red_factor1 * red1). For Sentinel-2 it gives (B5 - B4) as the last part of the equation. The difference is the / in MCARI and - in S2-MCARI. Is this a typo, as it should clearly be / in S2-MCARI as well? And is this typo implemented in the algorithm or is the algorithm correct (/)?

  1. Just as a remark:
    In the CI and BI help section, the source is given as (Escadafal, 1989). When searching online I only found this: . Is that really the source? That source doesnt even give an equation or even names the index “Brightness Index”. Also the source in the CI index help section (Pouget et al.(1990)) can be found nowhere online. Besides, there is no information on Brightness Index and Colour Index to be found online. Are they even scientifically proven?

Thank you very much

Regarding MCARI, the formula used in the algorithm is correct, the error is only inside the help. The help will be corrected, thank you for pointing it out.

Hello again,
Regarding your second point, I’m not an expert, but I’m guessing that those articles are written in french, so try searching after “indice de couleur IC” or “indice de brillance IB”.
You can also see: