Optimisation scene

[CLAN_VFX]

I have a question about optimisation.

My animation scene have many refractions with glossy effects like ice cubes, glasses, drops of water and liquids (realflow simulations). The output is 2k with motion blur and depth of field. GI is not used because all the scene is basically refraction and reflection.

I tried to decrease the subdivision of shaders/lights and set the image sampler to 48 or 64 (even 100) max subdivision to resolve the motion blur and depth of field, but the render time is still very high. I tried doing the opposite (shaders/lights high and image sampler low), but it didn't work either.

Do you have any advice on how to improve the render time?

[super gnu]

which version of vray are you using? rendertimes? machine spec? test frame we can see?

hard to advise with so little information.

bear in mind you are basically describing a really heavy scene. not everything can be made to render fast. glossy refraction is an absolute killer, and you are adding DOF and moblur on top of that. (on a side note, in most cases, you can use one or the other, only specific cases need dof -and- moblur, since both blur the scene)

did you try using refraction interpolation?

id say since everything is blurred, id lean towards low subdivs and let the image sampler handle it.

id also suggest trying the fixed image sampler, but it depends on how blurry everything actually is.

this is where a sample image would help.

[CLAN_VFX]

which version of vray are you using? rendertimes? machine spec? test frame we can see?

hard to advise with so little information.

bear in mind you are basically describing a really heavy scene. not everything can be made to render fast. glossy refraction is an absolute killer, and you are adding DOF and moblur on top of that. (on a side note, in most cases, you can use one or the other, only specific cases need dof -and- moblur, since both blur the scene)

did you try using refraction interpolation?

id say since everything is blurred, id lean towards low subdivs and let the image sampler handle it.

id also suggest trying the fixed image sampler, but it depends on how blurry everything actually is.

this is where a sample image would help.

Thanks for the reply!

My vray version is 3.00.03. Render times vary a lot, but are all very high, from 18 to even 40 hours per frame on i7 3930K.

I tried refraction interpolation but it introduced a lot of flickering.

I even tried to turn off DOF and MB altogether but render times are still high (not as high, tho, but pretty high still)

I agree that the main problem is in the glossy refractions, any advice on how to improve on that?

I'm attaching some sample images. Again, thank you very much for the help!

[super gnu]

hmm. ok so yes.. those are high rendertimes! your scene looks difficult, but i cant imagine that is the best time you can get.

im probably not the best to advise about scenes like this, but id definitely try the fixed image sampler. in scenes with a crapload of blurry effects it can be faster to just aa the whole thing at one level than to adaptively adjust..

id also say that high aa, low subdivs is preferable, as its all blurry. ( im struggling to remember if vray 3.00 has the subdivs for dof or not?) if you were on 3.2 id advise global subdiv multiplier at 0, fixed aa, and play with the minimum shading rate to see how it affects rendertime. care to upgrade? sure there will be some speedups to be had just from that.

i now open the floor to people who may have more experience in scenes like this....

[vlado]

Well, if you can get me a scene to vlado@chaosgroup.com, I can profile it and give you some advice on speeding it up.

Best regards,
Vlado

[CLAN_VFX]

Hi Vlado, That'd be great!

But do you need the full scene with maps and the .bin realflow files? If that's the case, maybe I could send you the .bin for just 1 frame because the full sequence is over 20GBs.

Thank you so much for the help!

[vlado]

But do you need the full scene with maps and the .bin realflow files? If that's the case, maybe I could send you the .bin for just 1 frame because the full sequence is over 20GBs.

Just one frame is fine.

Best regards,
Vlado

[CLAN_VFX]

I just sent it to you thru WeTransfer. If there are any problems with getting the file, please, let me know. Thanks!

[Morbid Angel]

I can also have a look if vlado is too busy

[bigbossfr]

I am interested to see the result of this optimization.
I know that refraction + glossiness is very difficult to optimize.