On-Orbit Spatial Quality Evaluation of SDGSAT-1 Thermal Infrared Spectrometer
Lintong Qi, Liyuan Li, Xinyue Ni, Xiaoxuan Zhou, Fansheng Chen
Abstract
The Sustainable Development Science Satellite (SDGSAT-1) was successfully launched on 5th November 2021. It is the world’s first scientific satellite dedicated to serving the United Nations 2030 Agenda for Sustainable Development. To evaluate the on-orbit image quality of its thermal infrared spectrometer (TIS), we propose an improved edge slope calculation method. Learning from past academic research, we found that the traditional edge slop (ES) calculation methods are limited by various factors. For example, it demands highly on geographical aspects and surface temperature uniformity. In this paper, we interpolate the narrow sea-land boundary region. The edge signal-to-noise ratio and dip angle are calculated by the selected region to determine whether it satisfies the conditions of ES calculation. The Otsu algorithm is used to find the optimal threshold for the sea-land division, and the sub-pixel edge positions are extracted by combining with the canny operator. In order to achieve higher precision, we use the modified Fermi function to fit the extracted edge spread function (ESF). During the on-orbit testing of the SDGSAT-1/TIS, we performed ES calculations for a large number of test areas with a flight direction of 0.5 and a scan direction of 0.45.