Rendering Speed

[Donfarese]

I noticed that vray RT 3.20.02 is quite a bit slower than Octane using full Pathtracing, or Brute Force + Brute Force. It's nice that Lightcache is faster but I tend to get certain issues with it, flickering in GI. Plus I can animate and render moving objects with just BR+BR with out shadow or GI flickering or issues. What is the reasoning for this and can vray increase it's speed for full Pathtracing to be less noisy faster? I tried coherent but it didn't really seem to help, in Octane we can set the actual Coherent ratio and it actually makes a huge difference. Anyway keep up the good work, thought I would give back some feedback that can maybe help vray become even better than it is.

[matanov]

Can you share this scene (peter.matanov@chaosgroup.com) ? I've tried some days ago few interior scenes with render settings close as possible and the results were quite opposite

[Donfarese]

Can you share this scene (peter.matanov@chaosgroup.com) ? I've tried some days ago few interior scenes with render settings close as possible and the results were quite opposite

I can try to put something together, I cannot release the scenes I'm working on right now. Are you sure your using vray BR + BR to Octanes Pathtracing? With Octane you set Coherent Ratio 0.5, GI Clamp 1.0, Caustics Blur 1.0, and it will render really fast. Trust me I would love to get vray even just as fast as Octane but I can't.

[savage309]

We can sign NDA, if that suits you. A sample scene would be nice, too.
Otherwise, there are too many different kinds of setups and scenes.
If we can take a look and try to match the settings and examine the scene in detail, that would help us figuring out whats going on.

[Donfarese]

We can sign NDA, if that suits you. A sample scene would be nice, too.
Otherwise, there are too many different kinds of setups and scenes.
If we can take a look and try to match the settings and examine the scene in detail, that would help us figuring out whats going on.

Okay let me see what I can do. Looking forward to figuring this out.

[Donfarese]

Here are to very simple examples, you can see the noise difference, and Vray looks to have incorrect light leakage in left upper ceiling. Both rendered at 2min 20sec. Now with detailed geometry, materials, and textures the gap widens quite a bit more.

[savage309]

Great, thanks for the scene.
I will forward that to the support for test and they will update you when we have something.

[Donfarese]

Great, thanks for the scene.
I will forward that to the support for test and they will update you when we have something.

Sounds good, thanks a lot bud! Like I said with more complicated scenes Octane starts really walking away with it. Also have the team look into why Lights are much much more noisy in renders in vray, with highlights on surfaces and such. something is really weird there. Looking forward to what they find!

[Donfarese]

Also what does NVidia's QMC sampling do for RT, I haven't noticed a speedup at all if it's included in the latest version 3.20.02.

[jacksc02]

your test scene is missing the ies file.

[Donfarese]

your test scene is missing the ies file.

Holy Crap Balls! Sorry about that.

[Donfarese]

Here are two more examples. vray 4min 7sec, octane 4min 4sec. Another thing is Octane is much smoother to work with, vray seems a little clunky with updating scene and stuff. Octane also renders scene evenly where vray renders from the center out for some reason which is a real pain, especially when you get uneven looking renders when ever you stop the render.

[savage309]

Thanks for the shot. Can you please send us a scene for that too at support@chaosgroup.com with link to this thread ? We would like to test that with different V-Ray settings and LC too. Is this the same scene you were get LC flickering ?

As for the update - V-Ray does not store the frame buffer on the GPU.
This way you are using the same amount of GPU memory for all kinds of resolutions, so you can make huge renders even on GPUs with small amount of memory and you can render as much render elements as you want without multiple render passes. Also you can render more stuff, since GPU memory is not used for storing pixels. This approach also provides somewhat better DR load balancing. The drawback is that we have to transfer results back to the CPU and this makes the update looking a bit slower.
We do not plan to keep the frame buffer on the GPU anytime soon however, since we consider the advantages of the opposite the better.

[Donfarese]

This scene I got Flickering with LC, for just test animation, not final renders. But I do notice there are area like around the ceiling spot lights that have light spots around them. do you think a GI clamp would help RT clean up the renders quicker, it does wonders for Octane.

[savage309]

This scene I got Flickering with LC, for just test animation, not final renders. But I do notice there are area like around the ceiling spot lights that have light spots around them. do you think a GI clamp would help RT clean up the renders quicker, it does wonders for Octane.

You are right, if we add cheats (clamps, post-process filters, ambient lighting, blurring glossy samples, AO), they will help with the render time, but all of them of course have drawbacks, too. And often render speed could be very different according to what amount of those cheats you apply. However, if you want fast (and biased) render, LC has one of the best benefits/drawbacks ratio. If you consider using that, you can check "Avoiding flickering in animations" here http://docs.chaosgroup.com/display/VRAY3/Light+Cache.

In the meantime, we will investigate the setup of the scene you provided and the support will update you with the results for the BF/BF GI. Also it is very important to match lighting, materials and settings as much as possible.
If you can send us more (under NDA), please do so at support@chaosgroup.com. Checking the settings people tend to use and being able to debug them helps us a lot.