The Moderate Resolution Imaging Camera (MoRIC) onboard the Tianwen-1 orbiter, China’s first Mars exploration mission, is a frame-imaging color camera. As of July 25, 2022, it has acquired a total of 14757 multiview stereo images covering the entire Martian surface. This letter proposes a scheme to construct a new global reference frame for Mars with a spatial resolution of several tens of meters using MoRIC images. It addresses critical issues, including on-orbit stereo imaging, tie points control network establishment, and global adjustment. Based on the photogrammetric global bundle adjustment technology with image data, the parameters, such as the internal and external orientation elements of the MoRIC images, have been significantly optimized. This has enabled high-precision positioning of images on the global scale of Mars, with a root mean square (rms) pixel residual of 0.9 pixels for tie points. A global orthophoto mosaic with a spatial resolution of 76 m and a geodetic control network have been established as a new Mars reference frame, providing a crucial foundational data for both Mars scientific exploration and engineering implementation.

High-resolution optical cameras have always been important scientific payloads in Mars exploration missions, and the Mars topographic data produced by their detection data can provide support for scientific research on Mars geomorphology and geological structure evolution. As of December 2021, there are still relatively few high-resolution image data at the sub-meter level on the Martian surface, with about 2.6% global coverage and even more limited stereo coverage (just about 0.4%). At the same time, there are still some difficulties in data acquisition and terrain reconstruction processing methods for high-resolution Mars images that need to be solved. This paper described how we designed the in-orbit stereo imaging strategy based on the characteristics of the High Resolution Imaging Camera (HiRIC) of China’s first Mars exploration mission (Tianwen-1), studied the technical solutions for HiRIC stereo image photogrammetry processing, and produced a topographic dataset for the “Tianwen-1” landing area, including digital orthophoto map (DOM) with a GSD (ground sample distance) of 0.7, 3.5m, and digital elevation model (DEM) with a GSD of 3.5m. Precision analysis results show that this topographic data has good consistency in planar position and elevation compared with the existing Mars terrain data, and has advantages in spatial resolution and terrain detail expression, which will be widely used in the geological background study of the “Tianwen-1” landing area, as well as landing site positioning, Martian surface remote operation planning and other Mars scientific research and engineering tasks.

The Chang’E-2 (CE2) lunar orbiter was the second robotic orbiter of the Chinese Lunar Exploration Program, as well as the pioneer robotic orbiter in the soft landing project in the second phase of the program. It used a two-line stereo camera to acquire stereo images with global coverage at a resolution of 7 m. The stereo images have a large potential for producing the best lunar topographic map. However, errors and uncertainties in the interior orientation (IO) and exterior orientation (EO) parameters of the camera seriously affected the accuracy of the global topographic mapping. In this paper, a global adjustment method is proposed to eliminate the effects of these errors. The error models are represented by a Chebyshev polynomial. The polynomial coefficients were estimated as unknowns using five lunar laser ranging retroreflector (LRRR) points as ground control points in the adjustment. The experimental results show that the planimetric and height deviations between the neighboring strips were 5 and 2 m (less than 1 pixel), respectively, which were decreased by 32.6 and 31.5 times, respectively, relative to those derived from the original EO parameters. The large inconsistencies in the CE2 trajectory data were significantly reduced after the adjustment. In comparison with the LRRR positions, the planimetric and height errors ranged from 21 to 97 m and −19 to 10 m, respectively. A new seamless mosaic and high precision absolute position topographic map has been generated using this method.

Due to repetitive patterns and gray changes in the remote sensing images, feature-point-based registration methods generally fail to determine every correctly matched point. In this letter, a novel registration algorithm that uses point structure information, which includes an improved shape context in feature description and consensus graph emerging from putative matches in feature matching, is proposed. First, to obtain robust initial matching point pairs, a DAISY descriptor is combined with a shape context descriptor that is improved using 1-D Fourier transformation. Second, the final matching results are estimated using graphic transform matching based on the local structure information of the point to remove outliers from initial correspondences. Finally, experimental results demonstrate that the proposed approach, based on structure information, is robust and can improve alignment precision in particularly complex environments.