essential
likely
maybe
probably not
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NDVI — formula and range?
Plain English (default view) — short, conversational, lightly seasoned with science
Plants pull a sneaky trick with light: chlorophyll **drinks red light** for photosynthesis but **bounces back invisible near-infrared**. NDVI just compares the two bands — the bigger the gap, the healthier the vegetation. Numbers land between **−1** (water / shadow) and **+1** (lush rainforest). The middle is bare ground. It's basically a 'how green is this place' score that NASA, USDA, and every satellite ag company uses every day.
🔬 Scientific / formula (revealed on click) — markdown + $$…$$ ok
**NDVI = (NIR − Red) / (NIR + Red)**. Range **−1 to +1**. Rouse et al. (1974). - Well-vegetated: high (0.6–0.8) - Bare rock/sand/snow: ≤ 0.1 - Water: negative
💡 Mnemonic / memory aid (shown on hover)
NDVI = Normalized to −1..+1. Unlike SR which has no upper bound, and unlike EVI which adds the Blue band.
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