VIGNETTING CORRECTION OF POST-EARTHQUAKE UAV IMAGES

Because of bad weather conditions after destructive earthquake, UAV images are captured with serious vignetting phenomenon, which can significantly affects the speed and efficiency of image mosaic, especially the extraction of geological structure information and also the accuracy of post-earthquake quantitative damage extraction. An improved radial gradient correction method (IRGCM) was developed to correct the UAV images sequence, which were obtained in Lushan County after Ms7.0 Lushan, Sichuan, occurred on April 20, 2013. The results show that the corrected images have better radial homogeneity and clearer details, to a certain extent, which reduces the difficulties of image mosaic, and provides a better result for further analysis and damage information extraction. Also, the IRGCM is more robust and faster for massive UAV images vignetting removal.