Hybrid mesh‐volume LoDs for all‐scale pre‐filtering of complex 3D assets

• Published in: Computer graphics forum Vol. 36; no. 2; pp. 431 - 442
• Main Authors: Loubet, Guillaume, Neyret, Fabrice
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.05.2017; Wiley
• Subjects: 3-D graphics; Albedo; Algorithms; Categories and Subject Descriptors (according to ACM CCS); Computer Science; Filtration; Finite element method; Graphics; I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism ‐ Raytracing; Image processing systems; Occlusion; Representations; Spatial resolution; Surface analysis (chemical); Three dimensional models; LoD; volume; hybrid; rendering; path tracing; trees; mesh
• ISSN: 0167-7055; 1467-8659
• DOI: 10.1111/cgf.13138

We address the problem of constructing appearance‐preserving level of details (LoDs) of complex 3D models such as trees. We propose a hybrid method that combines the strengths of mesh and volume representations. Our main idea is to separate macroscopic (i.e. larger than the target spatial resolution) and microscopic (sub‐resolution) surfaces at each scale and to treat them differently, because meshes are very efficient at representing macroscopic surfaces while sub‐resolution geometry benefits from volumetric approximations. We introduce a new algorithm that detects the macroscopic surfaces of a mesh for a given resolution. We simplify these surfaces with edge collapses and we provide a method for pre‐filtering their normal distributions and albedos. To approximate microscopic details, we use a heterogeneous microflake participating medium and we introduce a new artifact‐free voxelization algorithm that preserves local occlusion. Thanks to our macroscopic surface analysis, our algorithm is fully automatic and it generates seamless LoDs at arbitrarily coarse resolutions for a wide range of 3D models.