The clarity of remote sensing images is one of typical evaluation indicators for assessing the image quality of Earth-observation payload. The sharpness degree of imaging payload can be determined from the changing gray values at the edge of objects. Currently however

studies on orbit tests of Earth-observation payload and quality evaluation of remote sensing images focus mostly on whether the clarity values of the remote sensing images reach a certain standard. Very few of these studies conduct further analysis on the factors influencing the clarity of a remote sensing image. To address this issue

we assessed the clarity values of short-wave infrared (SWI) images of Tiangong-1 hyper-spectral payload in a long time series and analyzed the influencing factors on clarity. First

we calculated clarity using an improved clarity algorithm

which is based on image-edge detection. Then

the corresponding Tiangong-1 hyperspectral payload engineering parameters of the remote sensing images were obtained. Finally

association rule mining was performed using the typical Apriori algorithm on the clarity values of the SWI images of Tiangong-1 hyperspectral payload in the long time series and their corresponding engineering parameters. The association rules were viewed as alternative strong association rules when their supporting and confidence measurements exceeded the set minimum thresholds. Only the alternative strong association rules verified by the addition of the lift interest and cosine interest measurements could be adopted. The influencing factors on the clarity of the SWI images of Tiangong-1 hyper spectral payload were analyzed using the strong association rules and three-dimensional scatter plots. After testing a considerable amount of data

the results show that the clarity values of the SWI images of Tiangong-1 hyperspectral payload are good. The influencing factors on the clarity of the SWI images of Tiangong-1 hyperspectral images include solar angle

integral time

and platform stability (including the stability of pitch

yaw

and rolling angles). Solar angle is positively correlated with clarity. When the solar angle is larger than 65°

the clarity values tend to be higher

but when the solar angle is less than 30°

the clarity values tend to be lower. When the solar angle is larger than 30° and less than 65°

platform stability is positively correlated with clarity. Integral time has a negative relationship with remote sensing image clarity. The method of analyzing the factors influencing the clarity of SWI images of Tiangong-1 hyperspectral payload in a long time series is feasible and effective. The relationships between the clarity values of the SWI images of Tiangong-1 hyper-spectral payload and their corresponding engineering parameters have been identified. The scope of engineering parameters should be expanded to identify quantitative and more significant relationships. Furthermore

the association rule mining method could be helpful in analyzing the influencing factors for other remote sensing image evaluation indicators.