essential
likely
maybe
probably not
Front (prompt)
First vegetation index — history?
Plain English (default view) — short, conversational, lightly seasoned with science
🔬 Scientific / formula (revealed on click) — markdown + $$…$$ ok
**Simple Ratio (SR) = NIR / Red.** Originally used by Jordan (1969); Cohen (1991) called it *the first true vegetation index*. NDVI (Rouse 1974) fixed SR's unbounded range.
💡 Mnemonic / memory aid (shown on hover)
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