Absolute radiometric calibration is a process that relates measured camera digital number (DN) values to physical units of radiance. Absolute radiometric calibration is achieved by imaging a uniform light source with known radiance, and developing a conversion from measured DN to radiance. I2R uses NIST-traceable calibrated spectrometers to measure source radiance.

Absolute radiometry is important for quantitative remote sensing applications that require radiance or reflectance. Camera systems that have been radiometrically calibrated have consistent color balance, and are comparable with other calibrated camera systems.

• Enables time series assessments

• Improves change detection

• Required to generate valid vegetation indices

• Enables sensor-to-sensor comparisons