Nagano Akinori
Faculty of Sport and Health Science, Ritsumeikan University, Japan.
J Biomech. 2021 Nov 9;128:110722. doi: 10.1016/j.jbiomech.2021.110722. Epub 2021 Sep 4.
Direct linear transformation (DLT) is one of the most frequently used methods in motion analysis. This method was developed in 1971 and has subsequently been used in numerous studies. However, owing to the structure of the camera, unfavorable challenges are associated with this method. Because the DLT method is based on the structure of ordinary optical cameras in which the perspective projection is used, the camera's angle of view is limited. In this study, we propose a three-dimensional (3-D) calibration and reconstruction method using omnidirectional cameras, which have significantly wider angles of view than conventional cameras. For the interest points, the longitude and latitude of the celestial sphere are obtained from the image captured with an omnidirectional camera. The direction of the interest points relative to the camera's reference frame is determined via the longitude and latitude. In the calibration phase, the position and orientation of the omnidirectional camera relative to the global reference frame are determined from the image of the control points with known 3-D coordinates. In the reconstruction phase, the intersection point of the rays from the cameras is determined. Using an evaluation experiment, we verified the accuracy of the proposed method. The wide angle of view provided by omnidirectional cameras can be fully exploited using this method.
直接线性变换（DLT）是运动分析中最常用的方法之一。该方法于1971年开发，随后被用于众多研究中。然而，由于相机的结构，该方法存在一些不利的挑战。由于DLT方法基于使用透视投影的普通光学相机的结构，相机的视角有限。在本研究中，我们提出了一种使用全向相机的三维（3-D）校准和重建方法，全向相机的视角比传统相机宽得多。对于兴趣点，通过全向相机拍摄的图像获得天球的经度和纬度。兴趣点相对于相机参考系的方向通过经度和纬度确定。在校准阶段，根据具有已知三维坐标的控制点的图像确定全向相机相对于全局参考系的位置和方向。在重建阶段，确定来自相机的光线的交点。通过评估实验，我们验证了所提方法的准确性。使用该方法可以充分利用全向相机提供的宽视角。
