A few weeks ago, Dade introduced the new option for the CPU and openCL path render, so called hybrid or back-, forward or light tracking.
Since this introduction BiDir path (Bi-Directional / eye and light path) lost most of common interest. The new option is much faster than BiDir with same or even better quality in a lot of cases. Waiting for the end of a CPU BiDir render is no fun anymore. Too good and too fast is hybrid path openCL+CDPU rendering in combination with pgic for indirect light. One of BiDir's main weakness beside slowness is the lack of reasonably solving specular-diffuse-specular paths. BiDir fails to mirror a scattering light beam, something hybrid path does with ease.
Following and commenting this post here, dark juice
, yesterday, I got very curious about how to render correct looking orange juice in a glass in direct sun light. What I have observed during parameter search is quite a long story to tell. Let's begin with BiDir.
Render time for 800*600 picture is between 1 and 4 hours for at least 1000 up to 4000 samples.
Scattering Scale for all three picture is 500.
Heterogeneous Volume ss step size, ms max steps, ad absorption depth, scsc scattering scale
Metropolis mcr max consecutive rejects
Is mcr too small surface scattering of heterogeneous volume is not rendered. There is a difference between mcr 512 and 65536 but not much this means mcr 1024 to 4096 should be enough for this kind of set up.
However, the chosen parameters for the material are obvious a dead end. I required another approach. More about my findings in a next post.
160.8 | 42.8 (10.7) Gfp / Windows 10 Pro, intel i7 4770K@3.5, 32 GB | AMD R9 290x+RX 5700 XT, 4/8 GB
17.3 | 19.0 ( 4.7) Gfp / macOS X 13.6, iMac 27'', 2010, intel i7 email@example.com, 24 GB | ATI Radeon HD 5750, 1 GB
#luxcorerender | Gfp = SFFT Gflops