启明星一号夜间灯光影像的评估

Evaluation of Qimingxing⁃1 Nighttime Light Image

武汉大学研制的启明星一号(Qimingxing-1,QMX-1)卫星具备夜间可见光成像的功能,该卫星于2022年2月27日成功发射。为评估QMX-1夜间灯光影像的数据特点,选择北京市、深圳市和武汉市作为研究区域,将QMX-1夜间灯光影像与珞珈一号01星(Luojia1-01,LJ1-01)夜间灯光影像在数据统计特征、路网方面进行了多层次的对比分析,并利用小波分析评价启明星一号夜间灯光影像的空间特性。分析结果显示,QMX-1夜光影像与LJ1-01夜光影像灰度值分布不同,QMX-1夜光影像灰度值更加均一;QMX-1夜光影像中道路更易于辨认,且QMX-1夜光影像灰度值与道路长度和道路核密度具有更高的相关性;在QMX-1夜光影像上,23 m和46 m分辨率的小波分量均占约15%的能量,说明QMX-1夜光影像蕴含了丰富的空间细节信息。研究发现QMX-1夜光影像是一种质量较高的夜间灯光数据源,20 m左右空间分辨率的夜光数据能够更有效地反映城市细节信息。

Objectives:Qimingxing-1(QMX-1)satellite can obtain nighttime light images,which was de⁃veloped 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 ur⁃ban 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.