Coarse-to-Fine Crater Matching From Heterogeneous Surfaces of LROC NAC and Chang'e-2 DOM Images

The centers of matching craters can be beneficial additions to the control point database. Crater matching on heterogeneous surfaces is helpful in testing its applicability to the entire moon. Therefore, we propose a coarse-to-fine crater matching method for heterogenous surfaces on images acquired from the narrow angle camera (NAC) of the lunar reconnaissance orbiter camera (LROC) and the Chang'e-2 (CE-2) digital orthophoto map (DOM). First, we perform coarse matching based on the Hausdorff distance using the area and coordinates of the crater. Then, the mismatched craters are removed by using the affine transform (AT) model fitted by corresponding points of mutual information (MI) matching. Finally, we use the retained matched crater centers to fit the affine transformation model between the images, predict the corresponding position, and obtain the corresponding crater around it to achieve fine matching. The results show that the proposed method obtains numerous crater matches on images covering different terrains and solar altitude angles compared to the Hausdorff distance-based crater matching method. For the five experimental scenes registered using matched craters, the mean values of the checkpoints are approximately two and three pixels for scenes with small and large differences from CE-2 solar altitude angles, respectively, and the standard deviations (STDs) for both are approximately one pixel. In addition, the highlands have lower accuracy than the maria, with a variance of less than one pixel. Furthermore, the registration accuracy is related to the diameter and number of craters.

Automated summary

A coarse-to-fine method for crater matching on lunar images with different terrains and solar altitude angles was proposed, resulting in improved matching results.