The identification of the air–water interface in free surface flows traditionally involves intrusive techniques or costly equipment. Non-intrusive alternatives, such as computer vision, are emerging as highly effective substitutes or supplements for more invasive techniques in laboratory measurements, thanks to their straightforward implementation and cost efficiency. This research specifically delves in the conjunction of various naive techniques, exploring their collective precision in detecting the air–water interface along transparent walls in laboratory. A detection technique based on the double gradient of the image is applied and thoroughly examined. The study progresses through multiple refinement stages, culminating in a method that is both cost effective and easy to implement. This methodology allows for large-scale, high resolution measurements (200 mm × 1800 frames per video at a 0.25 mm, 50 Hz resolution), offering both spatial and temporal measurements by adeptly detecting the free surface along transparent walls.

中文翻译：

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使用经济高效的视频设备和计算机视觉技术，在实验室中沿着透明墙壁的几乎静止的流动中进行高时空分辨率自由表面检测


自由表面流中空气-水界面的识别传统上涉及侵入式技术或昂贵的设备。由于其简单的实施和成本效率，计算机视觉等非侵入式替代方案正在成为实验室测量中更具侵入性技术的高效替代品或补充。这项研究特别深入研究了各种简单技术的结合，探索了它们在实验室中沿着透明墙壁检测空气-水界面的集体精度。应用并彻底检查了基于图像双梯度的检测技术。该研究经历了多个细化阶段，最终形成了一种既具有成本效益又易于实施的方法。该方法可实现大规模、高分辨率测量（每个视频 200 毫米 × 1800 帧，分辨率为 0.25 毫米、50 Hz），通过熟练地检测沿透明墙壁的自由表面来提供空间和时间测量。