HIGH PRECISION DTM AND DOM GENERATING USING MULTI-SOURCE ORBITAL DATA ON CHANG’E-4 LANDING SITE
Chang’e-4 (CE-4) has successfully soft landed in Von Kármán crater inside the South Pole-Aitken (SPA) basin at 10:26 am on January 3, 2019. High precision landing site mapping plays an essential role in mission operations and science applications before and after landing. In this paper, we propose a novel method for generating the highest resolution and the best precision Digital Terrain Model (DTM) and Digital Orthophoto Map (DOM) of the CE-4 landing area using available multi-source data. First, the CE-2 DTM is co-registered to SLDEM2015. Then the vertical inconsistencies of the co-registered DTMs are analysed and the biases of CE-2 DTM with respect to SLDEM2015 are erased. Finally, a new DTM with more information and better precision is generated by fusion of the co-registered DTMs. Using the new DTM as a reference, a seamless DOM is generated based on block adjustment of projected imagery, which can reduce the inconsistencies among the corrected images to sub-pixel level. As a result, a DTM of the Von Kármán crater area ( 42º S–48° S/172º E–180° E) and a seamless DOM covering an area of 2.3° in longitude and 1° in latitude with a ground sample distance of 0.9 m are generated using the developed method.