CNES CO3D Image Ground Segment

Abstract. CO3D mission is a partnership between the French space agency (CNES) and Airbus Defense & Space, which aims at producing precise DSM (Digital Surface Model) data from optical stereo acquisitions by four satellites. The launch of the constellation was on July 25, 2025. A 6-months in-orbit commissioning period, including image quality calibration and validation activities, is being conducted. CNES is responsible for the performance of the CO3D system image products. To this end, it oversees the image performance and Digital Surface Model (DSM) activities and designs the operational computing software related to the image chain, which generates the 2D image products and 3D products. CNES thus develops the 2D and 3D image processing chain as well as the Image Calibration Center. This paper presents the composition of the L4 products (Surface Digital Model tiles), the algorithms, and the architecture of the image processing chain designed to meet production time and computational resource constraints. It also details the functionalities of the Image Calibration Center, its architecture, and the benefits gained from its deployment in the Cloud.