A pipeline-based heterogeneous framework for efficient synthetic light field rendering

Abstract

The research interest of real-time global illumination has increased due to the growing demand of graphics applications such as virtual reality. Recently, the design that combines Image-Based Rendering (IBR) and Ray-Tracing to create Synthetic Light Field (SLF) has been widely adopted to provide delicate visual experience for multiple viewpoints at an acceptable frame rate. However, despite its parallel characteristic, constructing a SLF is still inefficient on modern Graphics Processing Unit (GPU) due to the irregularities. For instance, the issues caused by branch divergence, early-termination and irregular memory access prolong the execution time that cannot be simply resolved by workload merging. In this paper, we proposed a Runtime framework that reorganizes the execution into a pipeline-based pattern with grouping of primary rays. The workloads are later distributed to all heterogeneous cores to increase the efficiency of the execution. With this approach, the number of valid rays can be maintained at a high level with less divergence of paths. Based on the experiment on a heterogeneous system, the maximum throughput for a single GPU becomes 3.12 times higher than the original on average and becomes even higher on systems with multiple heterogeneous cores.