[gene91]

There are two major approaches to rendering: rasterization and ray tracing. The former is faster, the latter is more real. They are completely different approaches.

Historically, ray tracing is only used for movies whereas games generally uses rasterization. The former is highly coherent workload, and is great for GPU. The latter is incoherent workload, and generally isn't suitable for GPU.

Games have started using ray tracing, and there have been GPU implementation of ray tracing in the past 5 or so years. What I said above may be stale.

[pcwalton]

Raytracing can absolutely be done on GPU even without RTX-style hardware; there are tons of implementations of it in the literature. Last I read the research, the best approaches dynamically bundle up rays hitting the same or nearby objects to squeeze coherency out of the GPU.

As far as I can tell, the biggest problem is simply that GPU raytracing requires a completely different software architecture. Giant boil-the-ocean rewrites that require not only new software but also new hardware are very difficult to justify, especially in a mature industry dominated by (relatively) short-term film production schedules. There are other technical issues too, such as VRAM limits.

[selectodude]

>Giant boil-the-ocean rewrites that require not only new software but also new hardware are very difficult to justify, especially in a mature industry dominated by (relatively) short-term film production schedules.

Anybody want to take my PhysX card off my hands? :)

[bhouston]

Yeah it is a bit stale. 3D artists these days want their render boxes to be filled with gpus so they can use cycles or redshift or octane to render fast. Old school artists use cpus these days.

[dagmx]

Completely untrue. Most feature films are CPU rendered. Good luck getting a lot of high end production scenes rendering on a GPU.

[glenneroo]

Since when was the discussion purely feature films? Our little studio can't afford racks full of Xeon CPU renderers, so we do as GP said, using redshift, etc. and just have a ton of GPUs.

[dagmx]

Because the commenter I replied to said that only old school artists render on the CPU. People pick the renderer that suits their needs, and it's not just a matter of old school people picking CPU pathtracers because it's what they know. You picked GPU rendering because you're, as you said, a smaller studio. That suits your needs. It's however not old school for big studios to use CPU rendering because GPU renderers just can't handle the scene complexity required yet.

[bhouston]

The reason why most artists highly prefer gpus is it gets their cycle time down. Farms often use CPU’s still because of cost and less pressure on a single image render time.

Usually what one does is break the shots down into individual elements rather than render everything as once and then composite it in. Rendering it all in one go can prevent touchups to individual elements. But I am much more VFX than pure animation - I think animation does more one shot one render work.

Funny thing I mostly know what I am talking about.

What studio do you work at?

[dagmx]

> Funny thing I mostly know what I am talking about.

You are only however talking about your subjective experience and projecting it onto the entirety of the industry.

I've worked in both animated features and VFX at a few of the bigger studios. What sort of studio do you work at?

I'd suggest looking at the landscape of big feature films and seeing what studios are using GPU rendering. It's rare to see any of the big studios using GPU rendering, not just because of existing farm hardware, but because none of the current GPUs and GPU renderers are capable of handling the larger scenes required, as well as losing out on some shader functionality like full OSL support among others...

If you look at the ACM breakdown of production renderers, in their rendering special, there's not a single GPU focused renderer there.

Individual artists may want GPU rendering. However your statement of only old school people using CPU rendering is just ignoring the realities of production.