Light field (LF) displays address the mismatch in focus cues present in traditional displays by triggering natural defocus blur and enabling motion parallax. They rely on geometrical optics, displaying rays from multiple angles of view. LF path tracing is computationally expensive for real-time applications, since it requires rendering multiple views. To reduce this computational complexity, spatially reprojecting pixels between views is commonly performed. Reusing pixels that are already rendered is cheaper than path tracing additional ones. However, when occluded areas are uncovered in some views, reprojection is not possible, creating holes in these views. Filling-in the holes requires extra path tracing computation. This paper investigates scalable hole-filling strategies for LF path tracing, using multiple GPUs to reach real-time performance. We propose an algorithm search optimization procedure to determine whether a specific assignment algorithm can be generalized across scenes, using the hole-filling time as a minimization function. In addition, we introduce DaSH (Discarded and Subsampled path traced Hole-filling), a novel method that reduces computation and divergence overhead in fixed-size hardware thread-blocks. Based on local pixel sparsity within pixel patches, DaSH adaptively subsamples and discards hole-filling rays. Our evaluation demonstrates that DaSH achieves significant performance gains while preserving the visual and structural quality of refocused light field images at the retina plane. The experiments demonstrate an average speedup factor of $1.8\times$1.8× for DaSH, compared to prior work, in a multi-GPU rendering system.

Stereoscopic and multiview rendering are used for virtual reality and the synthetic generation of light fields from three-dimensional scenes. Because rendering multiple views using ray tracing techniques is computationally expensive, the utilization of multiprocessor machines is necessary to achieve real-time frame rates. In this study, we propose a dynamic load-balancing algorithm for real-time multiview path tracing on multi-compute device platforms. The proposed algorithm was adapted to heterogeneous hardware combinations and dynamic scenes in real time. We show that on a heterogeneous dual-GPU platform, our implementation reduces the rendering time by an average of approximately 30%–50% compared with that of a uniform workload distribution, depending on the scene and number of views.

Path tracing combined with multiview displays enables progress towards achieving ultrarealistic virtual reality. However, multiview displays based on light field technology impose a heavy workload for real-time graphics due to the large number of views to be rendered. In order to achieve low latency performance, computational effort can be reduced by path tracing only some views (source views), and synthesizing the remaining views (target views) through spatial reprojection, which reuses path traced pixels from source views to target views. Deciding the number of source views with respect to the computational resources is not trivial, since spatial reprojection introduces dependencies in the otherwise trivially parallel rendering pipeline and path tracing multiple source views increases the computation time.