无需标定物,用运动信息自动校准事件相机与多传感器的时间和旋转偏差。
Temporal and Rotational Calibration for Event-Centric Multi-Sensor Systems
- 基于事件相机和其他传感器的旋转运动估计,直接从事件流中提取角速度。
- 在多个数据集上达到与依赖标定物方法相当的精度,且更稳定。
- 适合做事件相机系统集成的研究者,尤其关注鲁棒性与无标定场景应用。
事件相机以微秒级延迟响应像素亮度变化,为多传感器系统提供高时效感知;但其外参校准仍属研究空白。本文提出一种面向事件中心型多传感器系统的运动驱动时间与旋转校准框架,无需专用标定目标。方法利用事件相机与其他异构传感器各自的旋转运动估计作为输入,不依赖事件到图像帧的转换,而是通过事件数据的时空分布特征,高效估计角速度。整体流程分两步:首先基于协方差分析(CCA)思想,利用运动学相关性初始化时间偏移与旋转外参;随后采用连续时间参数化下的联合非线性优化进行精细校准。在公开及自采数据集上的大量实验表明,本方法精度媲美基于标定物的方法,且显著优于纯CCA方法,在精度、鲁棒性和灵活性方面表现优异。代码已开源:https://github.com/NAIL-HNU/EvMultiCalib。
原文摘要 · Abstract (English)
Event cameras generate asynchronous signals in response to pixel-level brightness changes, offering a sensing paradigm with theoretically microsecond-scale latency that can significantly enhance the performance of multi-sensor systems. Extrinsic calibration is a critical prerequisite for effective sensor fusion; however, the configuration that involves event cameras remains an understudied topic. In this paper, we propose a motion-based temporal and rotational calibration framework tailored for event-centric multi-sensor systems, eliminating the need for dedicated calibration targets. Our method uses as input the rotational motion estimates obtained from event cameras and other heterogeneous sensors, respectively. Different from conventional approaches that rely on event-to-frame conversion, our method efficiently estimates angular velocity from normal flow observations, which are derived from the spatio-temporal profile of event data. The overall calibration pipeline adopts a two-step approach: it first initializes the temporal offset and rotational extrinsics by exploiting kinematic correlations in the spirit of Canonical Correlation Analysis (CCA), and then refines both temporal and rotational parameters through a joint non-linear optimization using a continuous-time parametrization in SO(3). Extensive evaluations on both publicly available and self-collected datasets validate that the proposed method achieves calibration accuracy comparable to target-based methods, while exhibiting superior stability over purely CCA-based methods, and highlighting its precision, robustness and flexibility. To facilitate future research, our implementation will be made open-source. Code: https://github.com/NAIL-HNU/EvMultiCalib.
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