Heavy scene keeps using up all ram on machine and crashing, displacement

[emartin8907]

Hi,

I am trying to render a rather heavy scene- 8k res, with several 8k displacement maps, lots of refraction

It locks up while 'compiling geometry'. If I disable displacement this doesn't happen and it starts rendering within a few minutes.
My machine has 256gb of ram, and I am setting my dynamic memory limit to no more than half that no matter what it flys right past the limit every time until it's using all 256gb and just locks up.

I have displacement settings applied to the geometry, using Normal displacement, pre tessellated. Looks fine in RT at low res but won't render hi res.

Any advice would greatly be appreciated!

Cheers
Eric

[Morbid Angel]

well its probably view dependent tessellation at low res its subdiving way less then at 8k. You probably can just uncheck view dependent and treat the subdivs in scene units, or raise the view dependent value a lot higher for your 8k render.

[emartin8907]

Thanks Morbid Angel! That totally did the trick started rendering within a couple minutes, woooo! cheers!

edit- I didn't even have 'subdivision and displacement quality' enabled on my geometry, only had 'displacement control'. so I enabled subd and disp control as well, unticked View dependant and was good to go. Also lowered edge length a bit and increased subds a bit.

[Morbid Angel]

If you don't have explicit subdivision control node (which I would always recommend to have) it will default to globals which I think is set quite high (good for smaller res images). I think view dependent is still a better way bec it will subdivide further objects less. But I think some one mentioned that it should be in % of frame rather then pixel, for exactly situations like this.
Good luck!