OTOY Forums

Hi guys

I’m working on a GPU vs CPU rendering comparison which will be the subject of a podcast I’m working on with my colleagues. Every day I work as a support guy on a cloud render farm and I have my experiences with both CPU and GPU rendering (and I’ve seen experiences of our customers) but I’m very curious about your opinion.

If you use GPU render engines what are the reasons? The most common reason I’ve heard about is speed, but of course when you have access to more than one card or processor then I guess it’s rather speed\money.

What is interesting for me is are there any other reasons for using GPU render engines? Do they give a different, maybe cooler look, any features which CPU engines lack or type of subjects where they give better effects?

I’m very curious about your opinions and impressions when it comes to GPU rendering. What are the pros and cons?

By the way – when it comes to GPU unbiased engines – the GI and glossy reflections\materials highlights are computed as the same thing, right? For example, in CPU V-Ray GI and material reflections are visible on two separate layers\passes.

For our little shop, we moved away from Thinkbox Deadline managed local CPU+AWS CPU rendering to all local GPU rendering (at the time it was mostly VRay for Maya, and C4D's native renders) was not just for the cost, but the simplicity. We were some of the first Deadline users on AWS, using dynamically allocated spot instances. Because we already had developers working in that area on other projects, we had the in-house knowledge to make it work and be pretty cost effective. While it let us do things that would have been impossible/too expensive earlier, managing that CPU based system ate up huge amounts of human time and effort. Then a few years later, things shifted as half a dozen gaming GPUs working together could smoke a few hundred AWS CPUS. Add to that the simplicity of the way Octane's Network rendering is directly and instantly available to each artist, instead of assets and jobs and sub-tasks (and all the associated licenses) having to be carefully managed by a render wrangler (me), and the choice was clear.

As for the "look" of GPU, vs CPU, there's nothing that couldn't be done on either, if you have the time/money for it. The main "look" element is simply the speed of near instant feedback for lighting and texturing. For full frame sequence rendering, sure, I can throw 300 AWS CPUs at the job and get it back pretty fast, but that really doesn't help while building the scene. Fewer surprises and re-renders is a very good thing.