Sparse Voxel DAGs for Shadows and for Geometry with Colors
Licentiate thesis, 2018

Triangles are probably the most common format for shapes in computer graphics. Nevertheless, when high detail is desired, Sparse Voxel Octrees (SVO) and Sparse Voxel Directed Acyclic Graphs (DAG) can be considerably more memory efficient. One of the first practical use cases for DAGs was to use the structure to represent precomputed shadows. However, previous methods were very time consuming in building the DAG and did not support any other attributes than discretized geometry. Furthermore, when used for scene object representation, the DAGs lacked proper support for properties such as object colors. The focus on this thesis is to speed up the build times of the DAG and to allow other, important, attributes such as colors to be encoded.

This thesis is a collection of three papers where we in Paper I solve the problem with slow construction times while also further compressing the DAG, allowing much faster feedback to anĀ  artist making changes to a scene and also opening up the possibility to recompute the DAG in run time for slowly moving shadows.

If a unique color per voxel is desired, which uncompressed would require 3 bytes per voxel, we realize that the benefit from compressing the geometry (down to or even below one bit per voxel) is rendered practically useless. We thus need to find a way to compress the colors as well. In Paper IIA, we solve this issue by mapping the voxel colors to a texture, allowing for the use of conventional compression algorithms, as well as a novel format designed for real-timeĀ  performance. In Paper IIB, we further significantly improve the compression.

directed acyclic graph







Opponent: Ass.Prof. Jonas Unger, Linköping University - campus Norrköping, Sweden.


Dan Dolonius

Chalmers, Computer Science and Engineering (Chalmers), Computer Engineering (Chalmers)

Fast, Memory-Efficient Construction of Voxelized Shadows

IEEE Transactions on Visualization and Computer Graphics,; Vol. 22(2016)p. 2239-2248

Journal article

Compressing color data for voxelized surface geometry

Proceedings of the 21st ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games,; (2017)p. 13:1--13:10-

Paper in proceedings

Compressing color data for voxelized surface geometry

Subject Categories

Computer Engineering

Other Computer and Information Science

Media Engineering

Computer Science

Technical report L - Department of Computer Science and Engineering, Chalmers University of Technology and Göteborg University: 177


Chalmers University of Technology


Opponent: Ass.Prof. Jonas Unger, Linköping University - campus Norrköping, Sweden.

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