Objectives Qimingxing-1 (QMX-1) satellite can obtain nighttime light images, which was developed by Wuhan University and launched on 27 February 2022. In this study, we compare the QMX-1 nighttime light images with Luojia1-01 (LJ1-01) nighttime light images.
Methods The study selects the urban area of Beijing, Shenzhen and Wuhan as the study areas, and compares the two kinds of images in terms of statistical characteristics and road network analysis. Using wavelet decomposition to evaluate the spatial characteristics of QMX-1 nighttime light images.
Results The experimental results show that the digital number distribution of QMX-1 nighttime light images is different from that of the LJ1-01 nighttime light images. Besides, by comparing the coefficient of variation of four different surface feature types in the images, the pixel value of the QMX-1 nighttime light image is more homogeneous. For the road network analysis, the roads in QMX-1 nighttime light images are easier to identify, of which the digital number has a stronger correlation with road length and road kernel density. Additionally, in the QMX-1 nighttime light images, about 15% of the wavelet component energy is distributed in the 23 m and 46 m resolution, indicating that QMX-1 nighttime light images contain rich spatial details.
Conclusions The study shows that the QMX-1 nighttime light image is a nighttime light data with high quality, and nighttime light images with a spatial resolution about 20 m can effectively provide more detailed urban information.
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