A New Radiometric Correction Method for Multiple UAV Multispectral Images Under Varying Illumination Condition

Considering the spectral accuracy of UAV multispectral images is mainly influenced by the sensor factor and illumination factor, we separate radiometric correction into radiometric calibration and illumination and reflectance spectra separation (IRSS). Then focusing on the influence of varying illumination, we proposed the multiple-image IRSS (MI-IRSS) model for relative radiometric correction for multiple images. MI-IRSS can not only do a radiometric correction process for multiple images without irradiance measurement, but also can give a clear physical meaning which is illumination function to relative correction coefficients. Using reflectance images corrected by precise irradiance as validation data, the experimental results show that MI-IRSS can eliminate changes in radiometric level due to the varying illumination, with the mean root mean square error (MRMSE) of reflectance reaching 0.048, and the spectral angle mapping (SAM) between the estimated and measured illumination function reaching 0.154.