Satellite Imagery

Satellite imagery comes in several flavors. Optical multispectral imagery captures reflected sunlight in visible (red, green, blue) plus near-infrared (NIR) and shortwave-infrared (SWIR) bands, enabling computation of vegetation indices such as NDVI, NDRE, and EVI. Thermal imagery measures land-surface temperature (useful for detecting water stress before visible wilting). Radar imagery (Sentinel-1 C-band, ALOS L-band) penetrates clouds and measures soil moisture and crop structure — essential for cloudy regions where optical sensors fail for weeks.

The free-satellite revolution transformed agricultural monitoring. Sentinel-2 (European Space Agency) delivers 10-meter imagery with 5-day revisit globally, completely free. Landsat (USGS/NASA) has provided 30-meter imagery continuously since 1972, also free. MODIS delivers 250-meter imagery daily. Combined, these datasets enable field-level NDVI time series, multi-year trend analysis, and early-warning crop stress detection on any farm anywhere on Earth. Commercial constellations (Planet Labs with ~200 SuperDoves delivering daily 3-meter imagery) fill the resolution gap when 10-meter is too coarse for small fields.

Operational workflows include in-season crop monitoring (weekly NDVI flagging stress zones), yield forecasting (peak-canopy NDVI correlates with final yield at r² = 0.7–0.9 for most grains), disease detection (anomalous NDVI patterns + thermal signatures), boundary mapping (AI-segmented fields from imagery), and insurance claim validation. Challenges include cloud cover (typical 30–50% of acquisitions in tropical and temperate regions are cloud-contaminated), variable sun angle, and atmospheric correction complexity. WiseYield integrates Sentinel-2 imagery automatically for farms with GPS boundaries, calculating field-level NDVI time series and flagging zones where values drop significantly below the farm mean.