Normalized Difference Red-Edge
Normalized Difference Red-Edge (NDRE) is a vegetation index that uses the red-edge band instead of the red band used in NDVI. It is particularly sensitive to chlorophyll content in leaves and can detect variations in crop health and nitrogen status more effectively than NDVI, especially in moderate to high biomass conditions.
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
- crop health monitoring
- nitrogen status assessment
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
- Red edge bands are sensor-specific (Sentinel-2, WorldView-3) — limits sensor choice
What the values mean
| Surface type | Typical NDRE |
|---|---|
| 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 |
|---|---|---|---|
| Wyvern | (Band 23 - Band 18) / (Band 23 + Band 18) | RedEdge→Band 18, NIR→Band 23 | |
| ESA | (B8 - B6) / (B8 + B6) | RedEdge→B6, NIR→B8 | |
| MAXAR | (NIR1 - Red Edge) / (NIR1 + Red Edge) | RedEdge→Red Edge, NIR→NIR1 | |
| MAXAR | (NIR1 - Red_Edge) / (NIR1 + Red_Edge) | RedEdge→Red_Edge, NIR→NIR1 |
Spectral Band Visualization — Dragonette-1
Code Examples
Adapted for Dragonette-1 bands —
Frequently Asked Questions
What is the NDRE (Normalized Difference Red-Edge) and when should I use it?
Normalized Difference Red-Edge (NDRE) is a vegetation index that uses the red-edge band instead of the red band used in NDVI. It is particularly sensitive to chlorophyll content in leaves and can detect variations in crop health and nitrogen status more effectively than NDVI, especially in moderate to high biomass conditions. Vegetation indices quantify plant health, biomass, and photosynthetic activity by exploiting the contrast between how plants absorb visible light for photosynthesis and reflect near-infrared radiation from their cellular structure. NDRE is particularly suited for crop health monitoring, nitrogen status assessment, chlorophyll content estimation. The general formula is (NIR - RedEdge) / (NIR + RedEdge), which requires RedEdge and NIR spectral bands.
Which satellite sensors can I use to calculate NDRE?
NDRE is supported by 15 satellite sensors in our database, including Dragonette-1, Dragonette-2/3, Gaofen-1, Gaofen-2, GeoEye-1 and 10 more. Each sensor uses different band designations — for example, Dragonette-1 uses the formula (Band 23 - Band 18) / (Band 23 + Band 18), while Dragonette-2/3 uses (Band31 - Band22) / (Band31 + Band22). Select a sensor above to see its specific band mapping.
What spectral bands does NDRE require and why?
NDRE requires RedEdge (720-730), NIR (780-1400). Vegetation strongly absorbs red light for photosynthesis while reflecting near-infrared light from its mesophyll cell structure, making this contrast a reliable indicator of plant vigour.
How do I calculate NDRE in Python or R?
Both Python and R code samples are provided above. In Python, use rasterio to load individual band GeoTIFF files and numpy for the arithmetic. In R, the terra package handles raster operations efficiently. The key is to load bands as floating-point arrays to avoid integer division, and to handle division-by-zero cases where the denominator equals zero. For production use, consider applying a valid data mask to exclude no-data pixels before calculation.
How does NDRE compare to NDVI and other vegetation indices?
While NDVI is the most common vegetation index, NDRE exploits the red edge spectral region where vegetation reflectance changes rapidly, providing higher sensitivity to chlorophyll content than NDVI. The choice of index depends on your application, sensor availability, and atmospheric conditions.
NDRE 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
References
Need help choosing?
Ask our AI assistant for sensor recommendations, code examples, or how NDRE compares to other indices for your specific use case.