Load-Balanced Multi-GPU Ambient Occlusion for Direct Volume Rendering

Ambient occlusion techniques were introduced to improve data comprehension by bringing soft fading shadows to the visualization of 3D datasets. They consist in attenuating light by considering the occlusion resulting from the presence of neighboring structures. Nevertheless they often come with an important precomputation cost, which prevents their use in interactive applications based on transfer function editing. This paper explores parallel solutions to reach interactive framerates with the use of a multi-GPU setup. Our method distributes the data to the different devices for computation. We use bricking and load balancing to optimize computation time. We also introduce two repartition schemes: a static one, which divides the dataset into as many blocks as there are GPUs and a dynamic one, which divides the dataset into smaller blocks and distributes them using a producerconsumer way. Results, using an 8-GPU architecture, show that we manage to get important speedups compared to a mono-GPU setup.