火星快车HRSC线阵影像投影轨迹法近似核线重采样

Approximate Epipolar Resampling of Mars Express HRSC Linear Pushbroom Imagery Based on Projection Trajectory Method

火星快车高分辨率立体相机(high resolution stereo camera,HRSC)线阵推扫式影像具有分辨率高、全球覆盖性好等特点,对火星快车HRSC影像进行摄影测量处理可获取火星全球高分辨率地形数据,而影像匹配是自动获取地形数据的关键。利用核线几何约束可以将影像匹配搜索范围由二维降至一维。本文在构建火星快车HRSC线阵影像严格几何模型的基础上,提出了一种近似核线重采样方法。首先,利用投影轨迹法分析HRSC线阵影像核线的直线性与平行性;然后,将原始HRSC影像进行微分纠正生成水平影像,分析投影轨迹法得出的核线在水平影像上的几何关系并确定近似核线方向,再沿核线方向进行核线重排生成近似核线影像。实验结果表明,本文算法生成的近似核线影像同名点上下视差优于1个像素,且在水平影像上进行近似核线重采样减少了由外方位元素变化引起的几何畸变,更有利于影像匹配。

The High Resolution Stereo Camera （HRSC） on the European spacecraft Mars Express has high spatial resolution and global coverage. Thus, global high resolution topographic data from the Martian surface can be derived through photogrammetric processing of HRSC data. , butthe accuracy and efficiency of image matching can be improved with geometric constraints of the epipolar line. A approximate epipolar re-sampling method which is fit for HRSC linear pushbroom imagery is proposed. Firstly, the epipolar geometry of HRSC image is analyzed using a projection trajectory method.Then, the original HRSC images were differentially rectified into a normalized image. Next, the epipolar geometry in the normalized image is analyzed and the approximate epipolar line direction determined. Lastly, the epipolar image is generated through epipolar resampling in normalized image. Experimental results demonstrate the feasibility of the proposed methodThe parallax in the y direction is less than one pixel in the epipolar resampled image. Moreover, the geometric distortion is decreased when image matching is performed on normalized images.