Clean renders, activating gpus, and render times

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Clean renders, activating gpus, and render times

Postby EFS » Wed Jul 12, 2017 12:32 pm

EFS Wed Jul 12, 2017 12:32 pm
What settings need to be tweaked to get a clean (noiseless) render? Multiple tests ranging from 100-1000 rays (up to 12 minutes time) using Path Tracing are still yielding a very grainy render. I'm unclear what to tweak to make this go away.

Also, I have 3 gpus (1080gtx, 970gtx, 970gtx) but I can only activate two of them (1080 and 970). Any idea why the third gpu won't let me activate it? Clicking on its checkbox doesn't do anything ... it stays unchecked.

What is the speed boost multiple GPUs give? If I go from 1 970gtx to 2 970 gtxs, would that be a theoretical 200% speed increase, or is it fractional?

Lastly, what are the minimum recommended specs / settings for a 30minute long animation? Even at 1 minute per frame (much less than my current renders are taking, even with the noise), that would be 1minute x 24 fps x 60 seconds per minute x 30 minutes, which is 43200minutes or 720 hours or 30 full days ... which is way too long of a render time for an individual to realistically create a "show" type of thing. Especially when multiple takes to get it right are factored in. To get this down to even a 24 render period would be a 2second per frame render, and a 1 week render would be a 14 second render ... is that at all realistic for an individual using Unity to achieve? I was hoping that with over $1k of video cards things would be fast enough to render something with decent quality fast enough to create a "show" ... is this just way out of my $$$ league right now?

Using https://www.assetstore.unity3d.com/en/#!/content/50313 as a test, I'm getting between 2-12 minutes to render a frame, but thats still with noise, so I'm unclear if that time can go less because the problem is not related to rays or needs to be bumped up much more to become clean.

Sorry for the questions ... I'm a programmer by trade, so I'm unclear about what's realistically possible for an individual hobbyist using Unity + Octane.
Last edited by EFS on Wed Jul 12, 2017 12:56 pm, edited 1 time in total.
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Re: Clean renders, activating gpus, and render times

Postby Xhed » Wed Jul 12, 2017 12:55 pm

Xhed Wed Jul 12, 2017 12:55 pm
Could you export the scene as an ORBX file and try rendering it in standalone? I'm curious what the performance is there using the same GPUs.

What resolution and kernel are you for your render? 12 minutes sounds like a long time for a render.

The speed improvement of enabling a 2nd GPU is a little under 100%, due to overhead of adressing the 2nd GPU and the syncing.

The test build is limited in the number of GPUs, we only allow usage of 2. When we release the final product, there will be multiple subscription tiers with different capabilities, where you could enable >2 GPUs for Tier 3.
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Re: Clean renders, activating gpus, and render times

Postby EFS » Wed Jul 12, 2017 12:59 pm

EFS Wed Jul 12, 2017 12:59 pm
12 minutes with using 1k rays with Path Tracing using Digital Broadcast 1920x1080 resolution. Using 500 yields an approx 4-5 minute time. However, these are producing grainy results, so I'm unclear if I can go lower and fix the grain with a different setting, or if I need to go even higher (and make the render time even more). I got it down aprox 2 minutes with 200ish rays.

Again, I'm very new to this, and thus unclear of what settings to tweak here. Everything is basically the default for Path Tracing outside of the rays I'm changing.

[Edit - added resolution]
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Re: Clean renders, activating gpus, and render times

Postby EFS » Wed Jul 12, 2017 1:03 pm

EFS Wed Jul 12, 2017 1:03 pm
Here is an example of a render after it claims its finished.

Image

This was using Path Tracing, 500 rays. I haven't really changed anything else. Its a 4 1/2 minute render with grain ... which is both way too long if I wanted to produce an animation like mentioned above, plus its grainy.

Am I doing something wrong, or should a scene of this complexity with the gpus mentioned above be able to render cleanly at a *much* faster rate (thus making an animation doable?)
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Re: Clean renders, activating gpus, and render times

Postby Xhed » Wed Jul 12, 2017 1:18 pm

Xhed Wed Jul 12, 2017 1:18 pm
Are you having the same problem with other scenes?
Could you try disabling syncing of Unity data to Octane using the dropdown in the render view window (labled "Everything")?

EDIT: removed unneeded requests
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Re: Clean renders, activating gpus, and render times

Postby Xhed » Wed Jul 12, 2017 1:24 pm

Xhed Wed Jul 12, 2017 1:24 pm
You are using an indoor scene, so there's very little light coming into the scene, which results in a grainy image on a low sample count.
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Re: Clean renders, activating gpus, and render times

Postby EFS » Wed Jul 12, 2017 1:30 pm

EFS Wed Jul 12, 2017 1:30 pm
So I should increase the directional light strength and that should solve it? The room looks well lit to me, so I would have assumed that meant everything is fine ... but I'll give that a shot when I get into work.

Is there an approximate render time I should be shooting for with a 1080 and two 970s as my gpus for a clean render here? I simply don't understand what's realistic yet, so its hard to know what's due to my own mistakes and what's an actual limitation.

It would be great if there were a benchmark scene that could be run which says "with x gpu you should get y render time" that we could test against ... not having any real experience with 3d renders (I'm a programmer well versed in Unity and very minorly in 3ds Max), it would be very helpful to know what a properly set up render should look like using my machine.

[Edit -- Thanks for the help in understanding this.]
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Re: Clean renders, activating gpus, and render times

Postby ChrisHekman » Wed Jul 12, 2017 1:42 pm

ChrisHekman Wed Jul 12, 2017 1:42 pm
EFS wrote:So I should increase the directional light strength and that should solve it? The room looks well lit to me, so I would have assumed that meant everything is fine ... but I'll give that a shot when I get into work.

Is there an approximate render time I should be shooting for with a 1080 and two 970s as my gpus for a clean render here? I simply don't understand what's realistic yet, so its hard to know what's due to my own mistakes and what's an actual limitation.

It would be great if there were a benchmark scene that could be run which says "with x gpu you should get y render time" that we could test against ... not having any real experience with 3d renders (I'm a programmer well versed in Unity and very minorly in 3ds Max), it would be very helpful to know what a properly set up render should look like using my machine.



It is quite normal for a near noiseless render to take a while, especially on 1920x1080. The Pathtracing kernel is relatively fast, but that can still be quite slow.
Usually renders and animations are rendered offline in a renderfarm because of this. Some people also render overnight.

If physical correctness is not a major concern for you can try to switch the kernel to "Direct Lighting Kernel" and set Global Illumination Mode to Diffuse. (Or leave it on ambient occlusion)
This should converge much faster, and be faster in general. So you will be able to render more samples faster, and have less noise with fewer samples.
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Re: Clean renders, activating gpus, and render times

Postby Xhed » Wed Jul 12, 2017 1:46 pm

Xhed Wed Jul 12, 2017 1:46 pm
We have a benchmark tool where you can compare your relative performance against other setups.

You could try the direct lighting kernel in Diffuse mode, this should converge faster than the path tracing kernel.
Image

I've made a sample where you can see the difference between a closed and an open scene (with added point light) here. Both are rendered with 1k samples at 1920x1080 with the Path Tracing kernel.

PS: The scene takes me 4 ~ 5 minutes to render on a 1080Ti + Titan (Maxwell).
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Re: Clean renders, activating gpus, and render times

Postby EFS » Wed Jul 12, 2017 1:51 pm

EFS Wed Jul 12, 2017 1:51 pm
Thanks. I was hoping Unity would open the door for short film type renders for hobbyists, but it sounds like its really going to be used mainly for short cutscenes < 1 minute. Which, for a game engine, makes sense ;). Unless, of course, tweaking these things does wonders for render speed.

I'll check out the direct lighting kernel when I get a chance. Much appreciated.
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