We introduce a novel method for measuring properties of periodic phenomena with an event camera, a device asynchronously reporting brightness changes at independently operating pixels. The approach assumes that for fast periodic phenomena, in any spatial window where it occurs, a very similar set of events is generated at the time difference corresponding to the frequency of the motion. To estimate the frequency, we compute correlations of spatio-temporal windows in the event space. The period is calculated from the time differences between the peaks of the correlation responses. The method is contactless, eliminating the need for markers, and does not need distinguishable landmarks. We evaluate the proposed method on three instances of periodic phenomena: (i) light flashes, (ii) vibration, and (iii) rotational speed. In all experiments, our method achieves a relative error lower than 0.04%, which is within the error margin of ground truth measurements.

翻译：我们提出了一种利用事件相机测量周期现象属性的新方法，该设备可在独立运行的像素上异步报告亮度变化。该方法假设对于快速周期现象，在发生该现象的任何空间窗口内，会在与运动频率对应的时间差处生成一组非常相似的事件。为估计频率，我们计算事件空间中时空窗口的相关性。周期则根据相关响应峰值间的时间差计算得出。该方法无需接触，免除了标记物的需求，且不需要可区分的特征点。我们在三种周期现象实例上评估了所提方法：(i) 闪光、(ii) 振动及(iii) 转速。在所有实验中，我们的方法均实现了低于0.04%的相对误差，该误差在真值测量的误差范围内。