V-Ray Render Optimization - an in-depth Guide (call for Before/Afters)

[ben_hamburg]

Amazing Tutorial!

I´ve been dabbling with the settings for quite a while now, but due to tight deadlines I never found the time to actually do some heavy testing before submitting to the farm and hoping everything gets done in time...
For some projects with more organic stuff and little shadows and fine details we still come back to tha adaptive subdivision sampler, because it´s really fast there.

Like trixian before me, I´d also like to know how the "adaptive amount in the MDX sampler tab influences time and quality. Right now I just left it at it´s default of 0.85 and the noise threshold at 0.01.

By the way: Just recently I stumbled upon your tutorial about Displacement and that also shed some light at some of the issues I always had.

[RockinAkin]

Akin, could you post the render times together with these images? Are they dropping as the subdivs are increased?

The render times rise in that GIF because I'm raising the entire scenes subdivs together for the sake of showing the effect on the SampleRate render element.
Remember that a truly optimized scene will have varying Subdivs values as needed for each aspect of the scene. Globally raising them all together is bound to be giving some aspects of the scene much, much more samples than it really needs. But overall it's still much faster and cleaner than the universal settings method as you can see from this before / after optimization for that particular scene:

It is correct, yes. It explains things much more clearly than I could.

Great to have the 'Vlado Approved' stamp.

I´d also like to know how the "adaptive amount in the MDX sampler tab influences time and quality. Right now I just left it at it´s default of 0.85 and the noise threshold at 0.01

Right now I find that those settings work perfectly fine too, and there isn't much need in changing them. If you need less noise, reduce the image sampler's color threshold and raise secondary subdivs again. Though I do wish we had a SecondarySampleRate so we could see exactly what effect fiddle with those DMC values has... but I suspect very little.

[Morbid Angel]

I like the tutorial and explanation, its the method I've been using for a long time. I found though, it breaks apart when you use things like motion blur with depth of field, the render time when you increase shader subdivs becomes very high.

[vlado]

I like the tutorial and explanation, its the method I've been using for a long time. I found though, it breaks apart when you use things like motion blur with depth of field, the render time when you increase shader subdivs becomes very high.

This is also the case when you have a scene with many fine details that require lots of AA samples to clean up (f.e. fences, grass, hair, fine bumps etc). As with all things, it's a matter of balance.

Best regards,
Vlado

[glorybound]

If someone can give some real world examples; not balls and blocks, that would be wonderful. Load a scene up with displacements, trees and shrubs, HDRI, DOF, and at a high resolution. I'll continue to try to get better render times with faster renders, but I can't die on this hill. I think using the Sample Rate element pass is a good guide, but not a silver bullet.

[Morbid Angel]

This is also the case when you have a scene with many fine details that require lots of AA samples to clean up (f.e. fences, grass, hair, fine bumps etc). As with all things, it's a matter of balance.

Best regards,
Vlado

Which is exactly what I had on the last project. This method really did not work there, in fact, I've developed a hybrid method which would be a merge between universal and the method described here. This ended up giving me an acceptable result with in the acceptable time per frame.

[glorybound]

and that describes all my projects

[joconnell]

If someone can give some real world examples; not balls and blocks, that would be wonderful. Load a scene up with displacements, trees and shrubs, HDRI, DOF, and at a high resolution. I'll continue to try to get better render times with faster renders, but I can't die on this hill. I think using the Sample Rate element pass is a good guide, but not a silver bullet.

I've got something horrible - It's not trees and shrubs but it's something with lots of tiny details and even a 650 x 1000 pixel render is about 3 hours. The same rules as Akin's still apply, it's just a case of holding your nerve when things do start to get quite slow and accepting that there'll be some cases where there are scenes that any render will find incredibly nasty

[RockinAkin]

Morbid Angel and Glorybound -

The workflow isn't so much about a 'silver bullet' that will make any scene instantly render faster... it's about finding the ideal balance (as Vlado mentioned) between the Image Sampler and DMC Sampler to correctly address the different types of noise one can find in any scene.

As mentioned in the tutorial - some scenes will need more AA to clean up tiny details like foliage, dof, motion blur, etc. There's certainly nothing wrong with having higher AA values in these instances.
It's all about addressing noise at the specific sources it comes from, and assigning your sampling in the most efficient way to resolve it:
It's not going to be very efficient to assign more Image Sampler (AA) Subdivs to address noise in your lighting/shadows, gi, reflections/refractions. (as many people do when immediately adopting the Universal V-Ray Settings).
Just as it's not going to be efficient to assign more DMC Subdivs to address noise in your geometry and texture details, depth of field, and motion blur.

If you follow the workflow outlined in the tutorial, it should address the needs of any scene - one step at a time. After all, the very first step is to set your AA high enough to resolve the things you guys mentioned.

[glorybound]

I am getting somewhere with my scene, now. I got rid of my HDRI, which was in the vray sky dome and the environment, and replaced it with a vray sun/sky. Also, I turned off the reflection on my leaves and grass, which were not adding much value anyway. I'll do the sky and window reflections in post since this is a still. I also got rid of fresnel reflections on my materials and decreased the reflection color to close to black. I think, out of all the things I changed that made the greatest impact.

[voltron7]

Ivor 88 - Sweet results! Thanks for sharing!
Jorq1H - While that speed increase is ASTOUNDING... I agree with Morbid Angel that we'd need to fix the noise in the teapot's highlight before calling it a success. But luckily we know there's a TON of room for improving the optimized render given the difference in render times. Even so, that's totally nuts.


Here's an animated gif I've put together to illustrate how allocating more samples to the DMC Sampler reduces the stress on the Image Sampler.
The Image Sampler's Min & Max Subdivs stay the same, while the scene's Lights / GI / and Materials Subdivs rise... resulting in less Primary Samples (AA) being needed while quality improves.



(This scene generously provided by Peter Guthrie)

In this GIF, what is noise thresh and color thresh? Thanks for the great tutorial!

[RockinAkin]

^ Noise and Color threshold are both the default of 0.01. You're welcome!

[glorybound]

I went to bed last night excited, but woke up disappointed. I turned off all my trees, grass, and shrubs, and I optimized my house. Everything was going great; I was even able to drag my mouse around the screen, having the render keep up. The quality was awesome! So, I was rendering in practically real time, but the trees!!! Right before turning in for the night I turned my trees, grass, and shrubs back on. This morning I woke up to 8hrs and 14hrs to go. My little bucket buddies are slowly crawling over my trees. I thought I had my trees optimized. I turned down reflection, turned off filtering, and used them sparingly. From experience, proxies render slower, so they are not proxied. I would love some tips on how to get over this obstacle. Or, maybe a tree library that would be recommended.

[voltron7]

Bobby, did you tell trees to not generate GI?

[glorybound]

I did, but they got almost black, so I re-enabled it.

Bobby, did you tell trees to not generate GI?