Jatesiktat Prayook, Lim Guan Ming, Ang Wei Tech
Rehabilitation Research Institute of Singapore, Nanyang Technological University, Singapore 308232, Singapore.
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 637460, Singapore.
Sensors (Basel). 2024 Nov 21;24(23):7416. doi: 10.3390/s24237416.
This paper presents a calibration approach for multiple synchronized global-shutter RGB cameras surrounding a large capture volume for 3D application. The calibration approach uses an active wand with two LED-embedded markers waved manually within the target capture volume. Data from the waving wand are combined with chessboard images taken at close range during each camera's intrinsic calibration, optimizing camera parameters via our proposed bundle adjustment method. These additional constraints from the chessboard are developed to overcome an overfitting issue of wand-based calibration discovered by benchmarking its 3D triangulation accuracy in an independent record against a ground-truth trajectory and not on the record used for calibration itself. Addressing this overfitting issue in bundle adjustment leads to significant improvements in both 3D accuracy and result consistency. As a by-product of this development, a new benchmarking workflow and our calibration dataset that reflects realistic 3D accuracy are proposed and made publicly available to allow for fair comparisons of various calibration methods in the future. Additionally, our experiment highlights a significant benefit of a ray distance-based (RDB) triangulation formula over the popular direct linear transformation (DLT) method.
本文提出了一种用于围绕大型捕获体积的多个同步全局快门RGB相机进行3D应用校准的方法。该校准方法使用一个带有两个嵌入式LED标记的活动魔杖，在目标捕获体积内手动挥动。挥动魔杖的数据与每个相机进行内参校准时近距离拍摄的棋盘图像相结合，通过我们提出的光束平差法优化相机参数。通过在独立记录中与地面真值轨迹对比其3D三角测量精度（而非在校准自身所使用的记录上），发现基于魔杖的校准存在过拟合问题，而利用棋盘产生的这些额外约束来克服该问题。在光束平差中解决此过拟合问题可显著提高3D精度和结果一致性。作为此开发的一个副产品，提出了一种新的基准测试工作流程和反映实际3D精度的校准数据集，并将其公开提供，以便未来能够对各种校准方法进行公平比较。此外，我们的实验突出了基于光线距离（RDB）的三角测量公式相对于流行的直接线性变换（DLT）方法的显著优势。
