A vegetation index — 0 compatible sensors — Last revised June 1, 2025
RDI
Simple Ratio MIR/NIR Ratio Drought Index
A spectral index used for detecting drought conditions by comparing middle infrared and near-infrared bands. Useful for assessing vegetation stress and drought conditions using spectral reflectance measurements.
Used in crop monitoring.
When to use
- Time-series monitoring of crop health, growth stages, and stress detection
- Land cover classification and vegetation type discrimination
- Biomass estimation and net primary productivity studies
- Drought impact assessment over agricultural and forest areas
- Phenology tracking — green-up, peak season, and senescence
- Vegetation monitoring
- Drought detection
Limitations
- Saturates in dense canopies (LAI > 3) — values plateau and lose discrimination ability
- Sensitive to atmospheric scattering, especially blue-band haze
- Soil background contaminates measurements in sparsely vegetated areas
- Sun-sensor geometry (BRDF effects) introduces variability across acquisitions
- Cloud cover and shadows produce invalid pixels that need masking
What the values mean
-1 Water / Snow
-0.1 Bare ground / Built-up
0.1 Sparse / Stressed
0.3 Moderate vegetation
0.5 Healthy vegetation
0.7 Dense canopy
| Surface type | Typical RDI |
|---|---|
| Open water, snow | -0.3 to -0.1 |
| Bare soil, urban | -0.1 to 0.2 |
| Sparse or stressed crops | 0.2 to 0.4 |
| Healthy crops, grassland | 0.4 to 0.7 |
| Dense forest, peak season | 0.7 to 0.9 |
General Formula
Sensor-Specific Formulas
Most-used sensors — click to show code below
| Sensor | Provider | Formula | Band Mapping |
|---|
Code Examples
rdi_generic.py
RDI vs other vegetation indices
| Index | Name | How it differs |
|---|---|---|
| ARI | Anthocyanin Reflectance Index | Alternative vegetation index — different band combination |
| mARI | Modified Anthocyanin Reflectance Index | Refined formulation for specific conditions |
| ARVI | Atmospherically Resistant Vegetation Index | Atmospherically corrected version |
| ARVI2 | Atmospherically Resistant Vegetation Index 2 | Atmospherically corrected version |
Related Vegetation Indices
ARI
Anthocyanin Reflectance Index
mARI
Modified Anthocyanin Reflectance Index
ARVI
Atmospherically Resistant Vegetation Index
ARVI2
Atmospherically Resistant Vegetation Index 2
BGI
Blue Green Pigment Index
BNDVI
Blue Normalized Difference Vegetation Index
bNIRv
Blue Near-Infrared Reflectance of Vegetation
BRI
Blue Red Pigment Index
References
Pinder
J. E.; McLeod
K. W. (1999)
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