Indigo Renderer Forum

We present vertex merging - a bidirectional path sampling technique for Monte Carlo light transport integration. Vertex merging is simple and more computationally efficient for specular-diffuse-specular effects than the currently available techniques in bidirectional path tracing. It brings the advantages of photon mapping to the path integral framework, while avoiding the concept of density estimation altogether. This makes it possible for the first time to quantitatively reason about the efficiency of two rendering approaches that have been historically considered conceptually different. The practical result is a combined bidirectional rendering algorithm that efficiently handles a wide variety of lighting conditions, ranging from direct illumination and diffuse inter-reflections to the notoriously problematic reflected caustics. This algorithm also has a higher order of convergence than progressive photon mapping.

lycium wrote:SPPM isn't unbiased (it's consistent though), and its order of convergence isn't as good as BDPT in most respects, reflections of caustics being an exception

Combinatorial Bidirectional Path-Tracing
for Efficient Hybrid CPU/GPU Rendering

This paper presents a reformulation of bidirectional path-tracing that adequately divides the algorithm into pro-
cesses efficiently executed in parallel on both the CPU and the GPU. We thus benefit from high-level optimization
techniques such as double buffering, batch processing, and asyncronous execution, as well as from the exploitation
of most of the CPU, GPU, and memory bus capabilities. Our approach, while avoiding pure GPU implementation
limitations (such as limited complexity of shaders, light or camera models, and processed scene data sets), is more
than ten times faster than standard bidirectional path-tracing implementations, leading to performance suitable
for production-oriented rendering engines.

CoolColJ wrote:And something else of interest? No one has put out a GPU accelerated BPT renderer out yet... should be able to now