Where can I find Specular subdivs?

[3LP]

Hi guys,

We are in the middle of the process of optimizing a scene for animation.
And we just found out something really interesting : specular isn't related to any subdiv multiplier in the scene beside the global DMC sampler.
Let me explain : we went for the "keep low dmc sampler and adjust the materials accordingly" theory.
So we've got 1/4 in DMC and noise at 0.01. Adaptive 0.85 and global 1. Let's keep it easy, let's keep it as the defaults settings

All the mats have 8 in subdivs mainly and max depth to 2-3 and some of the main materials can go to 32-64 subdiv (floor, metals, etc)

With those settings, our average frame time was 3-4 hours for 720p = not acceptable.

So at this stage, we are going in cheat mode and start to take reflections off and try to fake the glossies. The solution would be to use specular! So I turn "trace reflection" off and start to play with specular to give the sheen I want to fake the blurry reflections.
Looks great, it takes me back in the days with standard mats, all good, BUT :

My speculars are noisy. -> So I go and up the subdiv of the reflection -> still noisy -> go to 512 subdiv -> still noisy -> heun???

So I figured out that the specular is only linked to the global DMC 1-16 makes it better, hitting 1-20 and the Sample rate pass shows orange specular, ok just under the bottle-necking of the dmc...

So, now, all my subdivs are probably way to high... So I've got 2 solutions :
1) turn the global subdiv down to compensate the increase of multiplication that I did with the DMC (this doesn't affect specular at all!)
2) manually turn all my materials down to hit the limit that I gave them in the first stage with 1/4.

My questions would be :

Why is the specular not being linked to the reflection subdivs?
Why is the specular not being affected by the global multiplier subdiv?
Why is the specular only affected by the global DMC sampler?
Where can I find any way of changing locally the specular subdiv?

Every other single thing in VRay lets you change locally the subdiv (light/mats/GI/lightmat as direct light/etc)
Why not specular? Even when the "trace reflection" is on, it still doesn't take the reflection subdiv into consideration.

Side question from there :
If I have my highlight reflection to lets say 0.6. And I push the subdiv of the materials to something crasy like 512, the whole point is having the blurry reflection smooth right? Well, how does VRay subdivide what info goes into the reflection pass and what goes into the specular pass?
Cause if at 0.6, 50% is send to the reflection pass and 50% is send to the specular pass, at 1/4 DMC I will push the subdiv of the reflection to try to smooth visually the blurry reflection. But practically, I will only affect the 50% of the reflection part and not the 50% of the specular part... So I will have to over sample the reflection to hope that having both together(specular not subdivided a lot) it will end up visually smooth.
This is really strange...

I hope I'm doing something wrong here otherwise I would be really surprised!

Sorry for the long message, I just wanted to be clear.

Stan

[psanitra]

Speculars are sampled by light subdivs, adjust those...

[alexyork]

I do wish that this could be controlled independently of the light samples, because often you'd like to "smooth out" those specular reflections without cranking up the shadow samples.

In general I hate specular with a passion...

[vlado]

I do wish that this could be controlled independently of the light samples, because often you'd like to "smooth out" those specular reflections without cranking up the shadow samples.

There is no way to do that unfortunately. And I mean no way whatsoever, not that it is just some limitation of V-Ray.

In general I hate specular with a passion...

There is no reason to do that either. What V-Ray calls "specular" is not the same thing as what you get in some other engines...

Best regards,
Vlado

[stevesideas]

I realise this is an old thread but I'm having exactly the same issues. My specular bokeh is proving to be very noisy. I've tried increasing the vray sun subdivs without success. I'm now going to try and lower my noise threshold in the image sampler.

[stevesideas]

It just seems to be the max subdivs in the image sampler is the only thing that reduces the noise in the bokeh. This is a bit of a nightmare because this affects every other channel and makes the renders take forever ! Surely there must be a way around this to only affect the specular. Even though the max subdivs are at 100 the bokeh is still noisy. I think I would have to increase to 200 or similar to have acceptable noise levels.

[joconnell]

Might be worth trying the subdiv multiplier in the right click > vray properties menu if it's a specific object / area which is noisy?