Black and blank render question

Schaaka

I understand these happen due to lack of GPU ram.

Silly question, is there a way to have Daz still render them? Like if you have 8gb of ram and a scene is 10 gb or ram, instead of the card just giving up can we make it where it would still render (albeit more slowly)?

Togire

If you have enough CPU RAM, the render can be done by the CPU at a much slower rate (CPU fallback). If you have not enough either VRAM or RAM, there is no way to have a faithful render as any part of the scene may influence the lighting of any other part. You can switch to simplified render methods like filament or 3DL or try to render separately different parts of the scene while hiding the others and combine the different parts in post work. There are also some tools to reduce the texture of items (and hence the memory print at the cost of rendering quality) like scene optimizer https://www.daz3d.com/scene-optimizer

Schaaka

The only issue I have with CPU fallback is that the cards will never run. I can have task manager open and see the activity is zero on my cards, unless if you happen to know a way that the cards can contribrute what they can instead of just quitting instead? 

I have a 3070ti (8gb of ram) and a 1080ti (10gb of ram). If the scene goes over 8gb of ram the 3070 will not even bother to work, if I go over 10gb I will get the black or blank render. If i put on cpu fallback neither card will do anything leaving me with a 4 hour render that looks pretty awful.

Instead of it being a binary 'work 100% or do nothing' situation, is there a way they can work together?

I'll give that scene optimizer a shot though, thanks on that one

Richard Haseltine

Task manager does not see the activity geenrated by Iray in the main listing - if you go to the Performance tab and set one of the graphs to CUDA you will see the card working (assuming it is).

Togire

Instead of it being a binary 'work 100% or do nothing' situation, is there a way they can work together?

You can have CPU and GPU used simultaneously, but ONLY if the complete scene fits in both RAMs. This will (very slightly) improve the computation time but in no way increase the available memory. The main problem of rendering is that is that it cannot be split in simple tasks distributed to independant processors.  A light will have impact on all the scene, illuminate walls, chars, etc, that in turn will reflect the light everywhere, and so on. So all the information must be available to every processor, hence the RAM requirements. For the same reason, if you have two GPU, they can be both used, but the one with smaller memory will limit the scene size.

Halcon Bluesky

@Schaaka, You have not mentioned what are the computer specs you have (Motherboard, Processor, Hard Disk, RAM) 

Without these details is not possible to pinpoint exactly to the problem you have.

Richard Haseltine

alainmerigot said:

Instead of it being a binary 'work 100% or do nothing' situation, is there a way they can work together?

You can have CPU and GPU used simultaneously, but ONLY if the complete scene fits in both RAMs. This will (very slightly) improve the computation time but in no way increase the available memory. The main problem of rendering is that is that it cannot be split in simple tasks distributed to independant processors.  A light will have impact on all the scene, illuminate walls, chars, etc, that in turn will reflect the light everywhere, and so on. So all the information must be available to every processor, hence the RAM requirements. For the same reason, if you have two GPU, they can be both used, but the one with smaller memory will limit the scene size.

In fact, at least on some systems, using the CPU as well as the GPU actually slows rendering down - perhaps because the CPU is bnoth allocating resourcs and acting as a resource, causing botlenecks.