REFLECTANCE CALIBRATION OF AERIAL VIDEO IMAGERY WITH AUTOMATIC GAIN COMPENSATION ON AND OFF

Video imaging systems are not radiometrically calibrated, thus it is d ifficult to obtain quantitative remotely-sensed imagery for natural re source applications. Video camera automatic gain controls (AGC) presen t potential problems in calibrating video systems for quantitative ana lysis because they compensate for changing solar illumination conditio ns. In this experiment aerial video calibrations to ground reflectance standards were compared for AGC turned on and off. The calibrated aer ial video was evaluated for guinea grass (Panicum maximum L.) biomass treatments on two dates. Results showed that there was more atmospheri c light scattering in the red than in the NIR video band. Light scatte ring affects could be detected only when the AGC was off because when AGC was on light scattering affects were masked. These results also sh owed that video imagery produced significant correlations with guinea grass biomass that were comparable to ground reflectance measurements.