NDVI — the Normalized Difference Vegetation Index — is the standard way to measure plant health from satellite or drone imagery. It's used everywhere from precision agriculture to deforestation monitoring, and the math behind it is simple. Getting the right bands, in the right order, out of a raw multi-band file is usually where people get stuck.
The formula, briefly
NDVI compares how much red light a surface absorbs against how much near-infrared (NIR) light it reflects. Healthy vegetation absorbs red light for photosynthesis but strongly reflects NIR, so the formula is:
The result ranges from −1 to 1. Dense healthy vegetation typically scores 0.6–0.9. Bare soil sits near 0. Water usually comes out negative.
Why band order trips people up
A multi-band GeoTIFF is just a stack of grayscale images — the file itself doesn't necessarily say which band is Red and which is NIR. Landsat, Sentinel-2, and a typical drone camera don't all order their bands the same way. Manually guessing wrong silently produces an NDVI map that looks plausible but is measuring the wrong thing.
There's a second, earlier version of the same problem: real Landsat and Sentinel-2 downloads from USGS EarthExplorer or Copernicus don't even arrive as one multi-band file — they come as several separate single-band files, one per band. Combining those into one file used to mean a detour through QGIS or GDAL before this tool could even open them.
How to do it
-
Upload your imagery
One pre-stacked multi-band GeoTIFF works, or separate single-band files (a real Landsat/Sentinel-2 download) — pick your imagery source for correctly-labeled upload slots, or assign bands manually for anything else.
-
Confirm the band mapping
Review the auto-detected Red/NIR assignment (and Green/Blue/SWIR if present for other indices), correct it if needed.
-
Run NDVI and export
Get a color-mapped PNG for quick visualization, plus the underlying GeoTIFF with the real NDVI values for further analysis in whatever software you use downstream.
Beyond NDVI
The same band-detection approach powers NDWI (water index) and NDBI (built-up/urban index), plus a False Color Composite for general visual interpretation — all in the same tool.
Ready to analyze your own imagery?
Open Raster Tools →