Comparison Between Pipelines

Currently, DiffRP supports two rendering pipelines: deferred lighting rasterization pipeline (diffrp.rendering.surface_deferred.SurfaceDeferredRenderSession) and path tracing pipeline (diffrp.rendering.path_tracing.PathTracingSession).

The deferred lighting rasterization pipeline (diffrp.rendering.surface_deferred.SurfaceDeferredRenderSession) supports PBR with image-based lighting, and can render various useful attributes like depth, world/camera-space normal, albedo, metallic/roughness attributes and so on. It supports analytical antialiasing and edge gradient methods as the visibility gradient. It requires nvdiffrast to be installed, which requires a working CUDA toolkit.

The path tracing pipeline (diffrp.rendering.path_tracing.PathTracingSession) is mainly targetting unbiased PBR. While the PBR rendering will produce albedo, world normal and first-hit positions as a by-product, rendering other attributes are not targeted by default. It is based on monte-carlo sampling of paths, so the PBR result would contain noise. You can use the denoiser, which is a differentiable version of a denoiser in OIDN, to denoise the result. It does not support common visibility gradient handling methods yet. It requires torchoptix to be installed for the best performance using RTX hardware, but can also run in pure PyTorch.