A rather simple pose estimator by tracking the horizon using OpenCV. It may have applications in AR and robotics when model, camera intrinsics/extrinsics and odometry information are missing.
A YouTube video from MotoGP rider Casey Stoner was used to demonstrate its performance.
OpenCV: I briefly experimented with solvePnP and solvePnPRansac, i.e., to find the pose from 3D-2D point correspondences. However, it was not straightforward to identify good correspondences for all frames given the many unknowns.