Absolute radiometric calibration and validation of a UAV multispectral sensor: a comparison between the irradiance-based method and reflectance-based method

Through an unmanned vehicle payload calibration campaign experiments, both reflectance-based and irradiance-based methods are used to calibrate multispectral sensor. The results show that both methods achieved good linear relationships between the digital numbers and apparent radiances (R2 > 0.99). Validation results demonstrated the relative error between the radiometric calibration and radiative transfer calculation ranged from 0.91% to 21.05%. The error analysis suggested that the irradiance-based method is less sensitive to aerosol parameters. However, the relative differences between these two methods are small under low aerosol loading conditions, suggesting the irradiance-based method may be a good option with some improvements.