Even though Non-rigid Structure-from-Motion (NRSfM) has been extensively studied and great progress has been made, there are still key challenges that hinder their broad real-world applications: 1) the inherent motion/rotation ambiguity requires either explicit camera motion recovery with extra constraint or complex Procrustean Alignment; 2) existing low-rank modeling of the global shape can over-penalize drastic deformations in the 3D shape sequence. This paper proposes to resolve the above issues from a spatial-temporal modeling perspective. First, we propose a novel Temporally-smooth Procrustean Alignment module that estimates 3D deforming shapes and adjusts the camera motion by aligning the 3D shape sequence consecutively. Our new alignment module remedies the requirement of complex reference 3D shape during alignment, which is more conductive to non-isotropic deformation modeling. Second, we propose a spatial-weighted approach to enforce the low-rank constraint adaptively at different locations to accommodate drastic spatially-variant deformation reconstruction better. Our modeling outperform existing low-rank based methods, and extensive experiments across different datasets validate the effectiveness of our method.

从时空建模的角度解决非刚性结构从动（NRSfM）中的关键挑战，包括运动/旋转的歧义、基于全局形状的低秩模型对3D形状序列的变形处理问题。通过引入新的临时平滑的Procrustean对齐模块和自适应的空间加权方法，提出了一种更好的非刚性结构建模方法，模型效果超过现有的以低秩为基础的方法。

非刚性运动三维重建：时间平滑的Procrustean对齐与空间变形建模