Optimising Brute Force for clean interior image

[coolhand78]

it seems that the incredible render times has to do with the vrayDisplacementMod...
are there any known issues with this in 3.2 or 3.3?

[Morbid Angel]

can you post a part of that scene for us to take a look?

[FSGFX]

have you tried to limited the max disp. subd.?
standard is 256.... try something like 16...

[glorybound]

Yes, displacement is a time killer. I just rendered a 6K exterior, without displacement, in around an hour. With displacement, easily 6+ hours.

[Morbid Angel]

I think there are steps to be taken to optimize displacement; its not something plug n play.

[Companioncube]

Yes, displacement is a time killer. I just rendered a 6K exterior, without displacement, in around an hour. With displacement, easily 6+ hours.

if your using 3D or subd displacement increase the edge length when you render your final full size image. i always have quite low displacement settings because i use it only for silhouette and large forms, usually blurring the texture quite a bit. can speed up the render a lot.

[super gnu]

also, i always subdivide the mesh to be displaced as finely as i can bear, prior to rendering. you can then reduce the max subdivs (possibly not even necessary) and the displacement mod has less tesselation to do. this can give big speedups.

[FSGFX]

if its statik geo you could also use the plugin for mudbox to create vray meshes... in this case you wont need dispmaps...
https://www.youtube.com/watch?v=kLwRlyxMquw

[coolhand78]

I've emailed the scene to chaos support, i've tried most things here but now my render times have blown out to 160hrs...

[vlado]

Thanks, will look into it.

Best regards,
Vlado

[FSGFX]

would be interesting whats causing this issues...

[coolhand78]

still working on this scene and it definitely appears to be a displacement issue...

seems i had left displacement on one tree and it killed my scene... remove the displacement and it appears to render normally...
haven't rendered the whole scene out but my initial test proved positive it got through the light cache in a reasonable amount of time...

will report back.

[Svetlozar Draganov]

How much memory do you have installed on the machine and how much of it is occupied during the rendering with and without displacement?
We've run some tests here and we didn't get any drastic difference in render time when displacement is turned ON and OFF globally.

[coolhand78]

Hi Svetlozar,

the machine has 32Gb of ram, i'll have to check about how much memory is being used when rendering. I think that i'd set the dynamic memory limit at 20000?
I was just shocked when it was saying that the render would take 221hrs @ only 3000px.

With the few objects in the scene that have the VrayDisplacementMod on them - the light cache takes a particularly long time to be built, however when the VrayDisplacementMod is removed the light cache builds "normally"... ie. rather quickly,
and it seems to render more "normally" (ie. at a speed most renders proceed at)...

[Svetlozar Draganov]

Thanks for the feedback.
In that case do we need to continue the investigation or we could mark this case as resolved?