The Methods of CE-2 Image Dense Matching and Lunar DEM Extraction

The two-line CCD stereo camera carried by the Chang E-2 (CE-2) satellite has successfully captured the global lunar imagery at 7 m resolution by the linear push-broom imaging manner. Compared with the image of Chang E-1(CE-1), the spatial resolution of CE-2 is greatly improved, which enables the more detailed presentation of the lunar surface features and topography, and consequently makes the production of high-resolution lunar DEM more complex and difficult. The existing methods based on the Chang E image can hardly meet the application requirements. In this paper, based on the previous studies on the characteristic of CE-2 image, we proposed methods of image matching and the Digital Elevation Model (DEM) extraction. The working flow started with the generation of the approximate epipolar images based on the RPC model and the construction of the pyramid images. By matching with the pyramid hierarchical, a pixel-wise matching of the original image was realized. We then calculated the three-dimension coordinates on the lunar surface of the matching points, and generated the DEM using the inverse distance interpolation method. Finally, the radial basis function interpolation was employed to fill the terrain hole caused by the image shadows. The results show that the lunar DEM generated by our method can accurately depict the most detailed and complete lunar surface topography, and perform better in the production of the global Lunar DEM products of CE-2 mission.