Deep Chessboard Corner Detection Using Multi-task Learning

Camera calibration is an indispensable step in the fields of robotics and computer vision, which includes augmented reality, 3D reconstruction, and camera motion estimation. Before camera calibration, detecting matching correspondence is necessary to understand the structure of the world from multiple images. For an accurate result, a calibration object, such as a chessboard, is used. Existing handcrafted feature methods precisely detect chessboard corners but are weak against blurs, noises, and severe lens distortion. Conversely, neural network-based methods can detect corners regardless of noises in the image. Both methods do not utilize the information of camera priors, which are lens distortion and intrinsic parameters, affecting the location of chessboard corners. Learning of lens distortion and intrinsic parameters enables the proposed network to understand the alignment of corners more precisely. Therefore, in this paper, we propose a novel multi-task learning framework to detect chessboard corners and simultaneously estimate lens distortion and intrinsic parameters. In order to train these three tasks, synthetic images of the chessboard are generated with ground-truth labels corresponding to each task. Hence, by learning the camera priors, the proposed network can more precisely locate the corners than other state-of-the-art corner detection methods while robust to noises, blurs, and distortion.