Rendering speed optimisation - many reflections

[thophile_dufresne]

Hello everybody,

Does anybody have some optimisation tips to share on how to render many reflections?
We are rendering an animation with a close up of christmas tree made of gold with depth of field.
With default settings (Min subdivs 1 Max subdivs 24 Threshold 0.050) [EDIT] Threshold is actually 0.010 [/EDIT] we have render time around 10 hours on the renderfarm for full HD.
Any ideas welcome on where to start looking for optimisation ?

Best,

[stezza]

Only apply depth of field in post, render out your Zdepth pass and comp it.

[Muhammed_Hamed]

10 hours is a lot with these settings, can you share a screen grab of one frame(beauty/sample rate/GI render elements if possible) ?
What tracedepth do you guys use ? and I guess you are rendering Depth of field in Vray ?
If you add a sample rate render element you will see which parts need more samples in red color, if you can share it will be helpful as well

There is not much to sampling/scene optimization in Vray, this is something Vray does very well
If the scene is lit mostly with GI, you can try and use direct lighting whenever you can. And the last option is to use DOF in post(if nothing else works) but honestly I wouldn't do that

Best,
Muhammed

[Karol.Osinski]

woah! Such a long render time with so high noise treshold. Maybe you could try lower max depth of your material reflections until you see very little / no difference in quality.

[thophile_dufresne]

Thanks for all the reply !
I will try to get out a frame with the different render elements.

[thophile_dufresne]

Hello,

I can't provide an image, but I found a solution !
The render time was so long because of one shader.
On my christmas tree, the tips of every pine needle are golden. I was using a Vray Blend Material. with one gold shader and one green shader
I switch to a single material with a ramp in the metalness/color, look the same and render much more faster.

Thanks again,

[seandunderdale]

Interesting....I use blend shaders A LOT and get fairly good render times on large automotive renders. I wonder what the specific issue was...

[Karol.Osinski]

Glad you managed to troubleshoot it man !!!! Yeah, gotta be careful with blend materials. I've made one with hand blown glass and it is literally x100 times slower than already, slow glass haha. Especially with CPU.

[piotrus3333]

pine needles are geo or made with opacity?

[Muhammed_Hamed]

There is probably something going on in the old setup, it is not supposed to render this slow
But I'm glad you got it solved