Camera Pose Estimation Using Images of Planar Mirror Reflections

The image of a planar mirror reflection (IPMR) can be interpreted as a virtual view of the scene, acquired by a camera with a pose symmetric to the pose of the real camera with respect to the mirror plane. The epipolar geometry of virtual views associated with different IPMRs is well understood, and it is possible to recover the camera motion and perform 3D scene reconstruction by applying standard structure-from-motion methods that use image correspondences as input. In this article we address the problem of estimating the pose of the real camera, as well as the positions of the mirror plane, by assuming that the rigid motion between N virtual views induced by planar mirror reflections is known. The solution of this problem enables the registration of objects lying outside the camera field-of-view, which can have important applications in domains like non-overlapping camera network calibration and robot vision. We show that the positions of the mirror planes can be uniquely determined by solving a system of linear equations. This enables to estimate the pose of the real camera in a straightforward closed-form manner using a minimum of N = 3 virtual views. Both synthetic tests and real experiments show the superiority of our approach with respect to current state-of-the-art methods.