An object's interior material properties, while invisible to the human eye, determine motion observed on its surface. We propose an approach that estimates heterogeneous material properties of an object from a monocular video of its surface vibrations. Specifically, we show how to estimate Young's modulus and density throughout a 3D object with known geometry. Knowledge of how these values change across the object is useful for simulating its motion and characterizing any defects. Traditional non-destructive testing approaches, which often require expensive instruments, generally estimate only homogenized material properties or simply identify the presence of defects. In contrast, our approach leverages monocular video to (1) identify image-space modes from an object's sub-pixel motion, and (2) directly infer spatially-varying Young's modulus and density values from the observed modes. We demonstrate our approach on both simulated and real videos.

翻译：物体的内部材料属性虽然肉眼不可见，但决定了其表面可观测的运动。我们提出了一种方法，通过物体表面振动的单目视频来估计其异质材料属性。具体而言，我们展示了如何估计已知几何形状的三维物体内部的杨氏模量和密度分布。了解这些属性在物体上的变化规律，有助于模拟其运动并表征任何缺陷。传统的无损检测方法通常需要昂贵仪器，且一般仅能估计均匀化材料属性或简单识别缺陷的存在。相比之下，我们的方法利用单目视频：（1）从物体的亚像素运动中识别图像空间模态；（2）从观测到的模态直接推断空间变化的杨氏模量和密度值。我们在仿真视频和真实视频上验证了该方法。