Creating high-fidelity 3D meshes with arbitrary topology, including open surfaces and complex interiors, remains a significant challenge. Existing implicit field methods often require costly and detail-degrading watertight conversion, while other approaches struggle with high resolutions. This paper introduces SparseFlex, a novel sparse-structured isosurface representation that enables differentiable mesh reconstruction at resolutions up to $1024^3$ directly from rendering losses. SparseFlex combines the accuracy of Flexicubes with a sparse voxel structure, focusing computation on surface-adjacent regions and efficiently handling open surfaces. Crucially, we introduce a frustum-aware sectional voxel training strategy that activates only relevant voxels during rendering, dramatically reducing memory consumption and enabling high-resolution training. This also allows, for the first time, the reconstruction of mesh interiors using only rendering supervision. Building upon this, we demonstrate a complete shape modeling pipeline by training a variational autoencoder (VAE) and a rectified flow transformer for high-quality 3D shape generation. Our experiments show state-of-the-art reconstruction accuracy, with a ~82% reduction in Chamfer Distance and a ~88% increase in F-score compared to previous methods, and demonstrate the generation of high-resolution, detailed 3D shapes with arbitrary topology. By enabling high-resolution, differentiable mesh reconstruction and generation with rendering losses, SparseFlex significantly advances the state-of-the-art in 3D shape representation and modeling.

翻译：创建具有任意拓扑结构（包括开放表面和复杂内部结构）的高保真三维网格仍然是一个重大挑战。现有的隐式场方法通常需要昂贵且会损失细节的封闭转换，而其他方法则难以处理高分辨率。本文介绍SparseFlex，一种新颖的稀疏结构等值面表示方法，能够直接从渲染损失中以高达$1024^3$的分辨率进行可微分网格重建。SparseFlex将Flexicubes的精度与稀疏体素结构相结合，将计算集中在表面相邻区域，并高效处理开放表面。关键的是，我们引入了一种视锥体感知的分段体素训练策略，该策略仅在渲染期间激活相关体素，从而显著减少内存消耗并实现高分辨率训练。这也首次实现了仅使用渲染监督来重建网格内部结构。在此基础上，我们通过训练变分自编码器（VAE）和整流流Transformer，展示了一个完整的高质量三维形状生成建模流程。我们的实验展示了最先进的重建精度，与先前方法相比，倒角距离降低了约82%，F分数提高了约88%，并演示了生成具有任意拓扑的高分辨率、细节丰富的三维形状。通过实现基于渲染损失的高分辨率、可微分网格重建与生成，SparseFlex显著推进了三维形状表示与建模的技术水平。