Branched PT

Hello friends
Did anyone have any success with getting better quality in the same amount of time by using branched PathPracing on GPU? Instead of using PathTracing on GPU.

I was glad when BPT appered in blender. By I was not glad that in didn’t help me at all in increasing quality and decreasing render time.

I’ve tried it several times and every time classic PathTracing was better in quality and in speed.

Maybe I did something wrong?

Does anyone have any example scenes?

I dont have any example scenes that i can share… but there was an internal shot with about 50 area lights… super noisy… enabling BPT with sample all direct lights / indirect lights… quickly made it clean.

But in general it just is simplier to use the normal PT samples then to set up BPT

It’s a must if you use SSS, mesh lights, volume… mainly differed, complex scenes.
Set it low on diffuse, glossy, transmission, AO, but set higher for subsurface, mesh lights & volume to get pleasing results & a balanced image. In this way branched is whole lot faster, better. Wouldn’t wanna have to do 2000 samples for diffuse & glossy if subsurface is only one that needs it. :eyebrowlift2:

One thing you do need to be wary of is if you are using the gpu for rendering and using windows… that windows will crash out if a sample takes longer then i think 3 seconds to process? you can extend this by changign the registry settings.

you may need to dial down the tilesize if this is the case.

I am using Linux

So. If a took it wright. BPT may be used when there is lots of SSS and mesh lights?I personaly try to never use meshlights.

Basically, it just gives you more control, more setting, needed just a bit more knowledge.
Though even having an option to set diffuse & glossy separately helps a lot with animations, where every second per frame counts. Then it will be noticeable. You’ll get to know it eventually. Major engines & studios all use it (with VRay, PRMan, Arnold, Hyperion…)
Would be best If you have a scene you’d like to test… can set it for you.
Or just watch: Cycles Render Settings Explained: Sampling and Light Paths

Be prepared to have a ton of RAM or so. Here on Linux,64bit, BPT renders for a while and then just crashes without telling much.

Yeah, I can’t render with 1 in every slot even, tried both progressive and non progressive. Simple scene (5 objects incl camera), but tons of unused materials. So, back to normal path tracing…

Edit: Oh, it worked if I turned off viewport rendering. (doh).
Edit2: It did not like 400 (total) glossy samples though (rest minimum). Crash.

What AA samples did you do? if you only had 4 aa samples and 100 glossy samples ofcourse its going to crash :stuck_out_tongue:

Well, sorry, I don’t know how the system is supposed to work :slight_smile: The simple test only had 4 metal objects (glossy shader only) in it, so I attempted to set it up so that everything else was pretty much ignored.

Why is it “ofcourse it’s going to crash”? I obviously must be missing something :smiley: