Dark Area glossy issue / long time render

[gkp]

Hi guys (i'm new here).

I work on a project


I have reflection/tiny bump/displace from zbrush/SSS.
I have some issue with dark area and glossy.
My render is pretty quick but in this area i have on or 2 bucket that take 10 to 30 minutes. (my render make aproximatly 30 minutes without that).



It's on my reflection, i try to add more AA subdiv or more relfection subdiv, work with a bigger resolution or low threshold.
All my map are convert to .tx or .tiledexr .
I work with Udim from mari and Zbrush , LWF. And i try to optimise why akin bilgic web site method's and his dmc calculator.
Maya 2015 / Vray 3.10

It's a neutral look dev scene with HDRI.
Do you have any idea for reduce render time for that ?
(I can send or post my pass scene or graph)

Thx !

GILBERT Kevin
Multiply Studio

[Morbid Angel]

I think its an issue with lightcache. If you use bf/bf does it still happen?

[gkp]

hi
You are right, I have check "Use light cache for glossy rays" but not "Retrace threshold". I have set 1500 subdiv LC . Down to 500 , my render time decrease, i have save twenty minute.
I have 30 minutes by frame(with 6 computers), still huge , but may be acceptable for a glossy render with SSS with a resolution of 1080.
(i gonna try to optimise again)

Thank you !

[Morbid Angel]

it shouldn't take this long for a simple render like that...

[joconnell]

No reason that should be as slow - great looking lookdev scene too, looks like it returns similar brightness values to the materials colours and there's some lights in there to create speculars too!

[gkp]

Thank for helping me,
I have done some test.
Without Scatter Gi , my render is much faster , 30 minutes with , 15 minutes without.
I use Brute force/ light cache. With a single Scatter on Simple mode.
AA 1/30 with a threshold 0.008 without AA filter.
I have fine detail on texture reflection Bump so i up my AA and for cleaning noise i raised material subdiv between 88 to 128.
I don't exactly know what subdiv is taken for calculate this pass, I guess is Gi subdiv. But Simple mode is link with the dome light subdiv if i'm not wrong ?
I certainly miss something.

[Morbid Angel]

just curious what kind of hardware you have? it seems excessively long with even 15 min per frame...

[gkp]

Hi ,
At home i have a I7 2,40ghz with 16 go RAM (it's a workstation dell precision) but i can work on mari without problem. At my office my workstation it's ok / I7 or xeon, with 16 or 32GO .

I think i have figured out my problem i have tiny detail in my displace and my bump so i have to up the AA to 22 ou 30 for cleaning geo and texture on the sample rate pass.
But for cleaning shadows of my HDRI i have to up subdiv to 300 with a threshold 0.010.
it's huge with a AA at 22 or 30.
May be i gonna make an other lighting but i'm interested to know what is making noise with hdri, is it super white to strong ? too much contrast ?

Thx

[gkp]

Hi again, When i spoke about tiny detail that can't be clearly seen with my actual Hdri.

[Svetlozar Draganov]

300 subdivs are quite a lot for any light and noise from lights is usually resolved with much smaller values.
Does the noise clear with less subdivisions if the HDRI-texture is removed from the light?

[KMPixelbox]

why do you use a displacement map? normal or even a bump map are enough for these small details.

[gkp]

HI, i use display from zbrush for sculpt detail and bump for tiny plastic detail

[gkp]

Hi, i finally , create a light set, my shadows was more hard , so my sss render more faster but have you some problem with high AA sample and sss ? I have to up my setting to 1/25 or on close up 1/40 for small detail.
i used raytrace sss on single scatter simple
on render region, my time without sss was 2 minutes and with 12 minutes , i don't oversampling material samples, i try 8 to 300 sudviv

[KMPixelbox]

can you post a sample scene?