NDVI as a calibrated spectral ratio
For compatible near-infrared and red surface-reflectance bands, NDVI=(ρ_NIR−ρ_R)/(ρ_NIR+ρ_R).
Key knowledge
For compatible near-infrared and red surface-reflectance bands, NDVI=(ρ_NIR−ρ_R)/(ρ_NIR+ρ_R). With nonnegative reflectances and positive sum it lies between−1 and1. The ratio can help characterize vegetation greenness, but does not uniquely measure biomass, plant health or a species. Common multiplicative scaling cancels; additive atmospheric effects do not generally cancel.
Values and equations
NDVI=(ρ_NIR−ρ_R)/(ρ_NIR+ρ_R)
- ρ_NIR,ρ_R
- compatible near-infrared/red surface reflectances 1
- NDVI
- normalized difference vegetation index 1
Conditions and scope
- Use the declared band's spectral response, product scaling, valid surface-reflectance pixels and positive denominator. Compare like geometry, atmospheric correction, season and spatial support; errors may produce nonphysical or unstable ratios.
- Soil background, water/snow, clouds, mixed pixels and canopy state affect the ratio. No fixed universal health threshold or guaranteed sensitivity at dense canopy is assumed; TOA or raw digital-number ratios are different data choices.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
US Geological Survey — Landsat Missions2 sources
Evidence and review
Read actual USGS surface-reflectance provenance, red/NIR formula and units; excluded current band/product specifications and universal health interpretation. The range and common-scaling cancellation are disclosed algebraic consequences with nonnegative/positive-sum hypotheses, not a guarantee for noisy corrected values.
2026-10-10 · Independent AI editorial review: All73 exact supplement compact statements, conditions, displayed equations and247 origin semantic links read; all109 combined original36+supplement73 author-source rows, exact locators, hypotheses, exclusions and disclosed derivations assessed. Original36 exact scientific content is independently approved in the linked receipt. All18 inherited Earth compact references and shared Math/Physics/Measurement methods were considered in the full practical Earth inventory. Targeted actual primary sections listed below; not every source body/proof or every possible university elective independently reread. AI editorial reference review, not human certification, full-degree proficiency, new experimental validation or a claim of whole combined Earth-and-Cosmos approval. Receipt: earth-completion-independent-content-inventory-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-ndvi-reflectance
- Revision
- core.1
- Structured reference record
- University core expansion