‹ back to GIS Glossary

Vegetation Index Mapping

Definition

Vegetation index mapping computes quantitative indicators of greenness, chlorophyll, or water content from multispectral imagery—NDVI, EVI, NDWI, and red-edge indices. Indices correct for illumination and atmospheric effects to varying degrees and summarize plant vigor over large areas. Time series reveal phenology, drought stress, harvest cycles, and disturbance.

Application

Agriculture manages irrigation and fertilization; forestry monitors logging and regrowth; urban planners track park health; and conservationists detect encroachment and fires.

FAQ

How do you choose among NDVI, EVI, and red-edge indices?

NDVI is simple and robust; EVI reduces saturation in dense canopies; red-edge indices are sensitive to chlorophyll in high-biomass or narrow-band sensors.

What steps ensure comparability across dates and sensors?

Use surface reflectance, consistent cloud/shadow masking, BRDF normalization where possible, and cross-sensor calibration.

How to separate phenology from sudden stress?

Compare anomalies to seasonal baselines (z-scores) and corroborate with weather or management records to avoid misattributing normal cycles.

What are limits of indices in heterogeneous urban scenes?

Mixed pixels and shadows can confound signals; high-resolution data or object-based methods help isolate vegetation from backgrounds.