Duan, YN; Yan, L; Yang, B; Jing, X; Chen, W (2013). Outdoor relative radiometric calibration method using gray scale targets. SCIENCE CHINA-TECHNOLOGICAL SCIENCES, 56(7), 1825-1834.
The radiometric calibration of remote sensors is a basis and prerequisite of information quantification in remote sensing. This paper proposes a method for outdoor relative radiometric calibration using gray scale targets. In this method, the idea of two substitutions is adopted. Sunlight is used to replace the integrating sphere light source, and gray scale targets are used to replace the diffuser. In this way, images at different radiance levels obtained outdoors can calculate the relative radiometric calibration coefficients using the least square method. The characteristics of this method are as follows. Firstly, compared with laboratory calibration, it greatly reduces the complexity of the calibration method and the test cost. Secondly, compared with the existing outdoor relative radiometric calibration of a single radiance level, it uses test images of different radiance levels to reduce errors. Thirdly, it is easy to operate with fewer environmental requirements, has obvious advantages in the rapid calibration of airborne remote sensors before or after flight and is practical in engineering. This paper theoretically and experimentally proves the feasibility of this method. Calibration experiments were conducted on the wide-view multispectral imager (WVMI) using this method, and the precision of this method was evaluated by analyzing the corrected images of large uniform targets on ground. The experiment results have demonstrated that the new method is effective and its precision meets the requirement of the absolute radiometric calibration.