Ego-Motion Estimation With Stereo Cameras Using Efficient 3D–2D Edge Correspondences

This article presents a new edge-based ego-motion estimation method for stereo cameras using 3D–2D edge alignment. To filter out prominent edgelets from Canny edge extractor, a region growing algorithm is developed to remove cluttered edges out of raw edgelets. Edge matching between stereo image pairs is guided by sparse feature correspondence using optical flow. The disparity is then refined using an inverse compositional algorithm, which is far more computationally efficient than searching along the epipolar line. The relative camera motion is solved by 3D–2D edge alignment based on an iterative closest point (ICP) algorithm, minimizing the point-to-tangent distance. A gradient-orientation-based similarity measurement is proposed, and the optimal correspondence is searched between the 3-D edge point projected onto the current image and the extracted edge pixels in the current frame with 1-nearest neighbor. In addition, the inverse depth of edge points in the reference frame is optimized. Experiments show that the proposed method can provide centimeter-level relative pose error (RPE), which has a better performance than the point-based approach efficient perspective-n-point (EPnP) and the edge-based approach direct edge-alignment (DE-A).