sky lobby

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lacilaci
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sky lobby

Post by lacilaci » Sat Jun 01, 2019 7:21 am

Hey guys,

I'm gonna do a project with a sky lobby style of restaurant.
I know luxcore can't handle this cause of missing features, but is there maybe a trick how to render this many light situation fast even without the ability to hide objects and lights from gi?

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B.Y.O.B.
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Re: sky lobby

Post by B.Y.O.B. » Sat Jun 01, 2019 7:36 am

Can you show some reference pictures of what you have in mind?
What exactly would be hard for LuxCore?
DLSC could be used to accelerate direct light sampling of many lights, while PhotonGI should take care of the indirect light.
Of course, this would require to use unstable beta software in production, which is never a good idea.
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lacilaci
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Re: sky lobby

Post by lacilaci » Sat Jun 01, 2019 9:53 am

https://images.app.goo.gl/CoPRk4Q2eRJSeMnf7

probably gonna be something like this, maybe on larger scale/space

I don't mind using alpha/beta software, I almost always do. But DLCS and glossy don't work so that won't work.

I have a certain freedom to how I build this place so maybe there is a place for compromise. With cycles I would use hidden simple lights that contribute to lighting and visible complex lights that don't contribute to lighting.

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Re: sky lobby

Post by Sharlybg » Sat Jun 01, 2019 2:54 pm

It is not the kind of work i will call hard for luxcore. But maybe you have some special way of doing things to achieve a given effects on your shaders or lighting.
Most of the time renderer seem to struggle when lights are very hard to reach or managed in a very complexe and heavy way (ex: thousands poly mesh light hidden behind complexe glass shader.)

For that kind of reason i always create my project in a way to cleverly avoid huge pression on the engine.This way i always render faster.
But sometime you can simply not avoid a given complexity and it at this moment i still believe a faster and stronger Bidir engine is a strength mostly when you consider monster 64 cores cpu with 128 threads.
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lacilaci
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Re: sky lobby

Post by lacilaci » Sat Jun 01, 2019 3:04 pm

Yeah, I'm gonna have to find a smart way around the issue to not make it hard on renderer. But there is no way I'm using bidir, that thing needs to stay in past where it belongs.

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Re: sky lobby

Post by B.Y.O.B. » Sun Jun 02, 2019 9:43 pm

I have roughly modelled the reference scene you linked so we have something to test.
By the way, the image is available in higher resolution here: https://images.app.goo.gl/ityAZY7JJR1EmkYj7

So far I have only done a quick render (about 3 min total, about 750 samples) with Path OCL + Sobol + PhotonGI.
I have split the different types of lights into lightgroups so I can better analyze where noise is coming from.

The ceiling spotlights contain a meshlight with disabled DLS (direct light sampling) and very low gain, just so the camera sees a white surface. Their main lighting comes from a spotlight positioned directly below the meshlight.

You can see that only two lightgroups are responsible for most of the noise:
- the pointlights in the lampshades
- the caustics from the wallspots

The caustics can probably only be disabled or clamped.
I will investigate the pointlights tomorrow, not sure yet how to optimize those.
Candles are also missing for now, as well as some furniture.
Attachments
fletcherHotel_02.blend
(673.24 KiB) Downloaded 24 times
combined
combined
denoised
denoised
ceiling spot meshlights
ceiling spot meshlights
ceiling spots (spotlights)
ceiling spots (spotlights)
lampshades
lampshades
sky
sky
wall spotlights
wall spotlights
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lacilaci
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Re: sky lobby

Post by lacilaci » Mon Jun 03, 2019 5:02 am

Thanks for testing it out. I'm gonna try something with those spotlights and clamping. This could have been so much easier.

By the way, for some reason if I try to stop render in your scene, blender freezes and I have to kill it. At first I thought it's the denoiser but it does it with denoiser turned off too!

Then I noticed it was because of intel's built in graphics enabled in devices! I had a recent bios failure and it seems intel's integrated gpu got re-enabled in bios. Maybe it could be fixed, but maybe it would be best if integrated gpus weren't listed at all as devices.

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lacilaci
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Re: sky lobby

Post by lacilaci » Mon Jun 03, 2019 5:16 am

What I really dont' get is that spotlights are noisy even where they directly hit objects.. wtf?

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Re: sky lobby

Post by lacilaci » Mon Jun 03, 2019 5:22 am

Low clamping values make spotlight look weird, but values over 1000 keep some fireflies/noise even after 2000 passes, not even mentioning that reflection of some objects won't get denoised :shock:

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Re: sky lobby

Post by B.Y.O.B. » Mon Jun 03, 2019 1:05 pm

lacilaci wrote:
Mon Jun 03, 2019 5:02 am
Then I noticed it was because of intel's built in graphics enabled in devices! I had a recent bios failure and it seems intel's integrated gpu got re-enabled in bios. Maybe it could be fixed, but maybe it would be best if integrated gpus weren't listed at all as devices.
I opened an issue about that: https://github.com/LuxCoreRender/BlendL ... issues/262
lacilaci wrote:
Mon Jun 03, 2019 5:16 am
What I really dont' get is that spotlights are noisy even where they directly hit objects.. wtf?
We could take a look at the spotlight sampling code.
I used very soft spotlight borders, maybe that's causing it?
edit: Nope, a single spotlight is clean at 1 sample, even with maximum softness. It's probably just the amount of lights causing it not to be picked very often.
lacilaci wrote:
Mon Jun 03, 2019 5:22 am
not even mentioning that reflection of some objects won't get denoised
Have you looked at the albedo pass, maybe it's still noisy? It's a known problem with glass that it causes noise in the albedo pass which really throws off the denoiser.
We could check if we can create the reflections some other way, e.g. use mirror with low opacity for the window glass.
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