Calculate memory required

[lander]

What's the general formula for calculating the memory needed for 1. Simulating a fluid sim
2. Rendering

I understand different channels would require different amount/voxel and that modulating the smoke/ opacity would also have to be considered.

Is there one so that I can estimate if I would be able to render using Gpu or cpu without testing?

[Svetlin.Nikolov]

Hey,

It is very complex. There was a failed attempt to estimate it and show it in the user interface, but it was misleading many people so I ended up removing it. Each simulation and rendering stage uses different amount of memory depending on many conditions, so there is no easy way to calculate it without actually running the sim.

Cheers!

[lander]

Yes I see. Will the render use the same amount of memory using cpu or gpu?
I have a render that is absolutely insane. And as I am about to invest in a new system I'm wondering how far I'll get with 24 Gb on a graphic card... It's never enough

[Svetlin.Nikolov]

Ah, it's different between V-Ray CPU and GPU in many cases as well:
- V-Ray GPU does not support sparse grids like V-Ray CPU does, yet, so if you arr loading huge sparse vdbs coming from other software, they will take up more space kn V-Ray GPU.
- V-Ray GPU does not utilize the Volume Light Cache, which otherwise uses a lot memory on CPU, and even more when render elements are required, so in this case V-Ray GPU is better.
- V-Ray GPU does not need the Optimize Big volumetric grids option, so it one again uses less memory.
- V-Ray GPU does not yet have the grid based self shadowing that V-Ray CPU has, so this is once again less memory with V-Ray GPU.

Hope this helps!