BidirVM is one of LuxCore's lesser-known features and was never shown in the addon, however it can be enabled by tweaking a few lines in BlendLuxCore. It works best when supplemented with metropolis light transport (MLT). Why use BidirVM+MLT for this scene?
- I used a smoke simulation and heterogenous volume setup for whole-scene atmospheric scattering. This is extremely computationally expensive, and makes denoising impractical.
- Reflective and refractive caustics are created by the highly specular vase, glasses, and a glass block window in front of the light source (for the left two images).
- SDS paths! Bidirectional and simple path tracing cannot reasonably converge SDS paths, even supplemented with metropolis light transport.