PhyRecon: Physically Plausible Neural Scene Reconstruction

While neural implicit representations have gained popularity in multi-view 3D reconstruction, previous work struggles to yield physically plausible results, thereby limiting their applications in physics-demanding domains like embodied AI and robotics. The lack of plausibility originates from both the absence of physics modeling in the existing pipeline and their inability to recover intricate geometrical structures. In this paper, we introduce PhyRecon, which stands as the first approach to harness both differentiable rendering and differentiable physics simulation to learn implicit surface representations. Our framework proposes a novel differentiable particle-based physical simulator seamlessly integrated with the neural implicit representation. At its core is an efficient transformation between SDF-based implicit representation and explicit surface points by our proposed algorithm, Surface Points Marching Cubes (SP-MC), enabling differentiable learning with both rendering and physical losses. Moreover, we model both rendering and physical uncertainty to identify and compensate for the inconsistent and inaccurate monocular geometric priors. The physical uncertainty additionally enables a physics-guided pixel sampling to enhance the learning of slender structures. By amalgamating these techniques, our model facilitates efficient joint modeling with appearance, geometry, and physics. Extensive experiments demonstrate that PhyRecon significantly outperforms all state-of-the-art methods in terms of reconstruction quality. Our reconstruction results also yield superior physical stability, verified by Isaac Gym, with at least a 40% improvement across all datasets, opening broader avenues for future physics-based applications.