Topic roadmap for vegetation indices.

• What they are — synthetic band-math layers (not measurements).
• Why they work — healthy vegetation’s low red / high NIR reflectance makes ratios diagnostic.
• What they correlate with — leaf area index (LAI), % green cover, chlorophyll content, green biomass.
• Which ones to know — Simple Ratio (first), NDVI (standard), EVI (improved for dense canopies).