This paper studies implicit surface reconstruction leveraging differentiable ray casting. Previous works such as IDR and NeuS overlook the spatial context in 3D space when predicting and rendering the surface, thereby may fail to capture sharp local topologies such as small holes and structures. To mitigate the limitation, we propose a flexible neural implicit representation leveraging hierarchical voxel grids, namely Neural Deformable Anchor (NeuDA), for high-fidelity surface reconstruction. NeuDA maintains the hierarchical anchor grids where each vertex stores a 3D position (or anchor) instead of the direct embedding (or feature). We optimize the anchor grids such that different local geometry structures can be adaptively encoded. Besides, we dig into the frequency encoding strategies and introduce a simple hierarchical positional encoding method for the hierarchical anchor structure to flexibly exploit the properties of high-frequency and low-frequency geometry and appearance. Experiments on both the DTU and BlendedMVS datasets demonstrate that NeuDA can produce promising mesh surfaces.

本文研究利用可微分射线投射进行隐式表面重建。我们提出了一种高保真表面重建的柔性神经隐式表示方法NeuDA，利用分层体素网格维护分层锚点网格。此外，我们还深入探讨了位置编码策略，并引入了一种简单的分层位置编码方法，以灵活利用高频和低频几何与外观的特性。实验证明，NeuDA可以产生有前途的网格表面。

NeuDA:高保真隐式表面重建的神经可变锚点