Noncontact measurements of spatially varied ground surface deformation during landslide motion can provide important constraints on landslide mechanics. Here, we present and test a new method for extracting measurements of rapid landslide surface displacement and velocity (accelerations of approximately 1 m/s²) using sequences of stereo images obtained from a pair of inexpensive, stationary 4K video cameras with nominal frame rates of 29.97 Hz. The method combines elements of Structure from Motion with those of optical flow to extract data on 3‐D evolution of the ground surface during slope failure. We apply the method to an experiment at the U.S. Geological Survey debris‐flow flume in which a high‐speed, liquefying landslide was triggered by gradually adding water to a 6‐m³ prism of loosely packed sediment on a 31° slope. Strip‐scanning lidar measurements made during the experiment corroborate our video‐based measurements, but the latter encompassed the entire landslide surface and were much lower in cost. Our video‐based measurements enabled computation of depth‐integrated landslide dilation/contraction rates. The range of computed rates was within the ranges inferred from independent measurements of evolving pore water pressures and reasonable estimates of the hydraulic permeability of the sediment. Dilation and contraction rates play a crucial role in landslide mechanics. The dilation and contraction we observe contradict the incompressible flow assumption used in many studies that have employed noncontact methods to infer landslide properties.

中文翻译：

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使用多视点视频重建快速滑坡的速度和变形

在滑坡运动过程中对空间变化的地表变形进行非接触式测量可能会对滑坡力学产生重要的限制。在这里，我们介绍并测试一种新的方法，该方法使用从一对廉价的固定4K摄像机（标称帧频为）获得的立体图像序列中提取快速滑坡表面位移和速度（加速度约为1 m / s ²）的测量值29.97赫兹 该方法将运动的结构要素与光流的要素相结合，以提取坡度破坏期间地表3D演化的数据。我们将该方法应用于美国地质调查局泥石流水槽中的一项实验，在该实验中，通过逐渐向6 m ^3内加水触发了高速液化滑坡散乱堆积的泥沙的棱镜，倾斜度为31°。实验期间进行的带状扫描激光雷达测量结果证实了我们基于视频的测量结果，但后者涵盖了整个滑坡表面，并且成本要低得多。我们基于视频的测量能够计算出深度综合的滑坡扩张/收缩率。计算速率的范围是从不断变化的孔隙水压力的独立测量值和对沉积物水力渗透率的合理估计值得出的范围内。膨胀率和收缩率在滑坡力学中起着至关重要的作用。我们观察到的膨胀和收缩与许多采用非接触方法推断滑坡性质的研究中使用的不可压缩流量假设相矛盾。