无人机下视地面图像的单应约束*

针对利用机载信息辅助特征匹配的问题，给出了利用导航系统等提供的机载信息计算地面图像单应矩阵的方法，分析了机载信息参数误差对根据单应矩阵计算得到的像素位置的影响，并给出了基于单应约束的航空图像特征匹配实验结果。结果表明该方法计算得到的地面图像单应关系对参数误差不敏感，可以为特征匹配等提供先验的约束信息。

Homography of UAV downward-looking ground images

To the issue of assisting feature matching using airborne information, this paper presented a method of estimation of homography between two ground images based on the airborne information such as from the navigation system. The pixel position of one image could be calculated using the pixel information of another image and the homographic matrix between the two images. It designed experiments to analyze the pixel-to-pixel correspondence error of the two images which was caused by the inherent error of the airborne information parameters. Also proposed the feature matching results based on homography of two images. The results show that those interference factors have negligible influences on the homography. Finally, demonstrated the estimated homography to be useful priori knowledge in the field of aerial image analysis based on the experimental result of images feature matching.