Deriving The Anisotropic Atmospheric Pointspread Function of Off-nadir Remote Sensing
Hu Baoxin1.2; Li Xiaowen1.2; Zhu Chongguang1; Alan H. Strahler2 (The Institute of Remote Sensing Appplications, CAS, Beijing 100101) (Center for Remote Sensing, Boston University, Boston, MA 02215)
One of the main difference between atmospheric effect on nadir and off-nadir observations is the adjacency effect. For nadir remote sensing,the adjacency effect is azimuthally isotropic, but in off-nadir remote sensing,the effect is azimuthally dependent and the contribution of the background in the direction of the observer is greater than others. In this paper,we consider the space composed by the sensor,the target pixel, and environmental pixel and use geometric relations to describe the single scattering of diffuse reflection from the environmental one toward the sensor,in order to get a first--order aproximation of the atmospheric PSF for off-nadir observation. Our approximation is compared with Monte Carlo simulation results. Then we design a Wiener filter to remove the adjacency effect on ASAS images. The correction results are evaluated by visual evaluation of image quality and the analysis of spatial correlation between pixels in the original,corrected offnadir and nadir images.