Compressed Multiresolution Hierarchies for High-Quality Precomputed Shadows

• Published in: Computer graphics forum Vol. 35; no. 2; pp. 331 - 340
• Main Authors: Scandolo, Leonardo, Bauszat, Pablo, Eisemann, Elmar
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.05.2016
• Subjects: Analysis; and texture; Categories and Subject Descriptors (according to ACM CCS); Coherence; Compressing; Computer graphics; Hierarchies; I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism-Color; I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism—Color, shading, shadowing, and texture; I.4.2 [Computer Graphics]: Compression (Coding)-Exact coding; Image processing systems; shading; shadowing; Shadows; Studies; Surface layer; Texture; Trees
• ISSN: 0167-7055; 1467-8659
• DOI: 10.1111/cgf.12835

The quality of shadow mapping is traditionally limited by texture resolution. We present a novel lossless compression scheme for high‐resolution shadow maps based on precomputed multiresolution hierarchies. Traditional multiresolution trees can compactly represent homogeneous regions of shadow maps at coarser levels, but require many nodes for fine details. By conservatively adapting the depth map, we can significantly reduce the tree complexity. Our proposed method offers high compression rates, avoids quantization errors, exploits coherency along all data dimensions, and is well‐suited for GPU architectures. Our approach can be applied for coherent shadow maps as well, enabling several applications, including high‐quality soft shadows and dynamic lights moving on fixed‐trajectories.