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Cycles render engine
show user profile  Sangre
I did some Cycles rendering recently using my GPU and CPU separately and combined and here's the results:
R9 270X overclocked to 1200 MHz GPU and 6000 MHz memory, rendered in 3m 13s, while staying at 50 °C at full load.
i7 4790k overclocked to 4 500 MHz, rendered in 4m 21s, while staying at 85 °C at full load.
Both rendered the same image in 2m 45s, while staying at 75°C (CPU) and 45°C (GPU) at around 90% load.
Thought that some of you might find these numbers interesting.
I know this has been discussed before but what are your thoughts on the Cycles engine and GPU based rendering in general?

Here's the render I used for testing:

read 627 times
5/5/2015 5:02:34 PM (last edit: 5/5/2015 5:04:04 PM)
show user profile  Nik Clark
Cycles is amazing. I love it. I love the materials in Cycles. The node-based system leaves a lot of space for exploration and invention.

My Nvidia 970 renders really quickly. In some cases, it's (guessing) ten times faster than CPU rendering.

I made this the other day. It rendered in just a couple of minutes on the GPU

read 615 times
5/5/2015 5:18:56 PM (last edit: 5/5/2015 5:51:37 PM)
show user profile  Garp
What's the current state of affairs for effects like caustics, subsurface scattering or atmospherics on the GPU?
What about difficult GI situations, like a busy room with the only light source coming through the window from an HDRi in the environment?
These were very problematic just a few years ago and I've now idea how it has progressed.

read 579 times
5/5/2015 8:07:28 PM (last edit: 5/5/2015 8:07:46 PM)
show user profile  Nik Clark
Cycles can handle the light through the window ok, especially as the next version, currently beta, has portals. Atmospherics can work with cycles too.

Caustics are still a problem for Cycles, as it has no MLT. It's coming at some point though. It's one of the two things it doesn't do well yet.

iray will also handle the light through the window quite well, as I remember.

I just did a few tests with cycles to see how well the things I said work actually work. Seems ok, but hardly a proper test of this.

read 553 times
5/5/2015 10:46:38 PM (last edit: 5/5/2015 10:56:24 PM)
show user profile  Nik Clark
Hey Sangre.

When doing GPU renders in Cycles, change the bucket size to 256. I've been doing some tests on optimisation, and I've found that setting this can drastically cut render times.

read 552 times
5/5/2015 10:51:27 PM (last edit: 5/5/2015 10:51:27 PM)
show user profile  Bolteon
^ That seems rather absurd.

-Marko Mandaric

read 548 times
5/5/2015 10:55:41 PM (last edit: 5/5/2015 10:55:41 PM)
show user profile  herfst1
Can someone explain what you're talking about. You're talking about gpu rendering and cycles and I'm not sure if this is hardware or software talk.
read 547 times
5/5/2015 10:55:43 PM (last edit: 5/5/2015 10:55:43 PM)
show user profile  Nik Clark
Bolte, I know. Something about how it uses memory on the GPU.

Set to 32x32, the dragon scene took 17 minutes. Set to 256x256 it took a couple of minutes. Seems to be the same with all scenes.

Herfst, Cycles can use the CPU or GPU for rendering. The results are pretty much identical, just a huge jump in speed when using a decent GPU.

read 542 times
5/5/2015 10:59:01 PM (last edit: 5/5/2015 10:59:01 PM)
show user profile  Garp
Hey Nik, thanks for the tests :)
Your two renders with GI look really clean. Did you encounter any difficulty (blotches, not enough light in the recessed area, etc) or did they come up clean pretty much out of the box?

edit: I suspect GPU rendering is not associating one thread per bucket but rather one thread group (what CUDA calls warp, a group of 32 threads working in SIMT). That would explain the speedup with larger buckets.

read 522 times
5/6/2015 12:01:08 AM (last edit: 5/6/2015 12:06:07 AM)
show user profile  LionDebt
noob question time! Can it use both CPU and GPU simultaneously?
read 519 times
5/6/2015 12:04:12 AM (last edit: 5/6/2015 12:04:12 AM)
show user profile  Nik Clark
Hey Garp, no problem. The only thing I had to tweak was the samples for the diffuse bounces. When it's set too low, you get more noise. I upped it to a few more samples, and it was ok. I think you are right with your assumption of why it's faster.

LD, sadly not. I think getting it to work in parallel would cause problems, and to be honest, the GPU is a heck of a lot quicker. I think using the CPU would probably slow it down, as odd as that seems.

read 512 times
5/6/2015 12:11:01 AM (last edit: 5/6/2015 12:13:00 AM)
show user profile  herfst1
So this is a blender thing or can I get it on Max? I did a google search and blender came up in all the links I saw.
read 507 times
5/6/2015 12:15:06 AM (last edit: 5/6/2015 12:15:06 AM)
show user profile  Nik Clark
Sorry mate. It's Blender only so far. I don't think there are plans to make it separate.

read 504 times
5/6/2015 12:17:10 AM (last edit: 5/6/2015 12:17:10 AM)
show user profile  Garp
I don't think Blender devs are too concerned about making their code available as plugins for commercial apps ;)
I might be wrong, though.

read 500 times
5/6/2015 12:19:37 AM (last edit: 5/6/2015 12:19:37 AM)
show user profile  Nik Clark
Yeah, they are the tree-hugging open-source, socks and sandals types :)

read 498 times
5/6/2015 12:20:57 AM (last edit: 5/6/2015 12:20:57 AM)
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