Fig. 1. （a） The surface reflectance radiance （clear），（b） cloud reflectance & scattering （thin cloud），（c） cloud molecule scattering & radiance（thick cloud）

Fig. 2. The relationship of scattering angles with 865nm polarized reflectance for liquid droplets and ice crystals respectly in cloud

Fig. 3. Three geometrical factors may affect cloud fraction changes with viewing zenith angle

Fig. 4. The principal of multi-directional viewing by polarization spectral radiometer

Fig. 5. Pareto optimal front in objective space

Fig. 6. The Knee on Pareto optimal front

Fig. 7. Pareto optimal front of R670 dataset 1.A-knee （ideal solution）

Fig. 8. The results of cloud detection on dataset 1 for POLDER product （up），and for the proposed method （down）

Fig. 9. The results of cloud detction on dataset 2 for POLDER product （up），and for the proposed method （down）

Fig. 10. Synthetic image from original reflectance at 443,565,670 band （left）， the binary image of cloud detection by the proposed method（right）

Fig. 11. Multi-spectral contribution to cloud detection through the proposed method on DPC