arXiv:2409.06030cs.GRcs.CV2024-09被引 3

用局部显式曲面相交构建3D形状表示,兼顾精度与多种操作支持。

NESI: Shape Representation via Neural Explicit Surface Intersection

  • 通过双高度场与局部高度场相交构造形状边界
  • 在相同参数量下,误差显著低于当前最优方法
  • 适合需要同时支持体素查询和参数映射的场景

紧凑、准确且可直接在压缩形式下高效处理的3D形状压缩表示,在数字媒体应用中极为重要。现有方法多聚焦于学习得到的隐式或参数化表示:隐式表示适用于内外查询,但缺乏自然的2D参数化,不利于纹理或法线映射;参数化表示支持后者,却难以进行占用查询。本文提出一种新型学习方法NESI,基于局部显式(即高度场)表面的交集。由于显式表示可自然地同时表达为隐式与参数化形式,NESI能直接支持比隐式方法更广泛的处理操作,包括占用查询和参数访问。输入形状由一组不同方向的高度场有界半空间通过体素布尔交集表示。首先用一对反向高度场紧密包围输入,形成双高度场(DHF)外壳;再通过与捕捉内部表面区域的额外局部高度场相交来精炼该外壳。最小化所需高度场数量,并将DHF外壳与局部高度场以定义在R²子域上的神经函数紧凑编码。这种降维编码带来高质量的紧凑近似。在相似参数量或存储容量下,与当前最优方法相比,NESI显著降低了近似误差,尤其在低参数量时优势明显。

原文摘要 · Abstract (English)

Compressed representations of 3D shapes that are compact, accurate, and can be processed efficiently directly in compressed form, are extremely useful for digital media applications. Recent approaches in this space focus on learned implicit or parametric representations. While implicits are well suited for tasks such as in-out queries, they lack natural 2D parameterization, complicating tasks such as texture or normal mapping. Conversely, parametric representations support the latter tasks but are ill-suited for occupancy queries. We propose a novel learned alternative to these approaches, based on intersections of localized explicit, or height-field, surfaces. Since explicits can be trivially expressed both implicitly and parametrically, NESI directly supports a wider range of processing operations than implicit alternatives, including occupancy queries and parametric access. We represent input shapes using a collection of differently oriented height-field bounded half-spaces combined using volumetric Boolean intersections. We first tightly bound each input using a pair of oppositely oriented height-fields, forming a Double Height-Field (DHF) Hull. We refine this hull by intersecting it with additional localized height-fields (HFs) that capture surface regions in its interior. We minimize the number of HFs necessary to accurately capture each input and compactly encode both the DHF hull and the local HFs as neural functions defined over subdomains of R^2. This reduced dimensionality encoding delivers high-quality compact approximations. Given similar parameter count, or storage capacity, NESI significantly reduces approximation error compared to the state of the art, especially at lower parameter counts.

3D表示显式模型神经几何

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