Mid-low latitude LOLA terrain maps of the Chang’e-6 sampling area through batch self-constrained adjustment and fusion with the SLDEM

The Lunar Orbiter Laser Altimeter (LOLA) is currently the most precise spaceborne laser altimeter in lunar exploration. The digital elevation model (DEM) generated from the laser points obtained by LOLA is also the highest-precision global lunar terrain dataset available to date, and is widely used as foundational data in lunar research. However, given the uncertainties in orbit determination and the deviations in laser pointing, some of the laser profiles exhibit geolocation errors. Furthermore, due to the inherent characteristics of the polar orbits of spacecraft, the gaps between laser profiles gradually increase as the latitude transitions from polar to mid-low latitude regions. These factors collectively lead to artifacts and data voids in the original LOLA DEM. In this paper, to address these issues, we first propose a batch self-constrained adjustment method that separates tracks with significant anomalies for individual adjustment based on their slopes and evaluates the point density of each track to select the appropriate adjustment strategy. For the gaps between laser profiles, the Selenological and Engineering Explorer (SELENE)/Lunar Reconnaissance Orbiter (LRO) digital elevation model (SLDEM) is introduced as an additional data source. In this process, a co-registration method is used to reduce the inconsistencies between these two datasets. The effectiveness of the method proposed in this paper was verified in both polar and mid-low latitude regions. Finally, a high-precision terrain map of the Chang’e-6 sampling area located in the South Pole-Aitken basin was generated using the designed block processing scheme.