Landsat 8 band combinations :

1. Natural Color 4 3 2
2. False Color (urban) 7 6 4
3. Color Infrared (vegetation) 5 4 3
4. Agriculture 6 5 2
5. Atmospheric Penetration 7 6 5
6. Healthy Vegetation 5 6 2
7. Land/Water 5 6 4
8. Natural With Atmospheric Removal 7 5 3
9. Shortwave Infrared 7 5 4
10. Vegetation Analysis 6 5 4

First you imagine a mapping from wavelengths to color.

For example, at 470 nm (+/- 20) is considered Blue, at 540 nm (+/- 20) Green, 680 nm (+/- 20) Red, from outside 780 nm upto 1 milimeter is InfraRed (divided furthermore into Near InfraRed - NIR, Middle, Thermal, Far IF etc.).

Note that I am using the normal perception of color, i.e the RGB scheme. Then looking at the spectral specs of Sentinel-3, we can approximately classify bands Oa-3 and Oa-4 as Blue, bands 5 and 6 as Green, 7 to 11 as Red, 12 to 16 as "between Red and NIR", and bands 17 to 21 as NIR. Now you apply the "Band ratio" in RS as for ex NDVI=(NIR-Red)/(NIR+Red), Land-water index=NIR/Green etc.

CUSTOM SCRIPTS

Wildfire visualization:

• Level 1 - R5 G4 B3
• Level 2 - R4 G3 B2