More than one question (Hybrid Back/Forward path tracing)

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Noah_
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More than one question (Hybrid Back/Forward path tracing)

Post by Noah_ » Tue Jan 28, 2020 3:48 am

Hi! :D


I'm new is lux and I wanted to know a few things about Hybrid Back / Forward path tracing (aka BiDir without MIS) and other things :?:

1. Is this rendering method suitable for animation? :?

2. Is Bidir support dead? :?:

3. With this method you can see the caustics in mirrors? :!: If not, how would it be possible?

4. Is it possible to caustic metal objects? for example a sword or katana

5. What is the limit of the caustics of lux with those of the real world?

6. Can you put imperfect surface textures?

7. Is there a possibility that Bidir will be faster with more development?

if I can think of more questions I say them

I want to congratulate the developers for working on such a beautiful render engine that can generate spectacular caustics and to Sharlybg for the tutorials, thank you very much I learned some things :mrgreen:

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Dade
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by Dade » Tue Jan 28, 2020 9:23 am

Noah_ wrote:
Tue Jan 28, 2020 3:48 am
1. Is this rendering method suitable for animation? :?
There have been reports of caustic intensity variations in animations. I have never been able to replicate this problem. But in any case, it is a bug, not an intrinsic limit of the method.
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
2. Is Bidir support dead? :?:
No but it lacks significative advantages over Hybrid Back/Forward path tracing: it is mostly slower.
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
3. With this method you can see the caustics in mirrors? :!: If not, how would it be possible?
Yes if you enable caustic cache too.
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
4. Is it possible to caustic metal objects? for example a sword or katana
Yes.
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
5. What is the limit of the caustics of lux with those of the real world?
None I can think to.
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
6. Can you put imperfect surface textures?
Yes.
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
7. Is there a possibility that Bidir will be faster with more development?
No, BiDir traces about n^2 rays where n is the max. path depth while hybrid about n.
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Noah_
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by Noah_ » Tue Jan 28, 2020 12:35 pm

Dade wrote:
Tue Jan 28, 2020 9:23 am
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
1. Is this rendering method suitable for animation? :?
There have been reports of caustic intensity variations in animations. I have never been able to replicate this problem. But in any case, it is a bug, not an intrinsic limit of the method.
This worries me in a way because I see a lot of potential in this for animations.

Is it still working to resolve this error or does it have to do with the hardware of certain computers?
Full Hybrid Back/Forward path tracing - I don't like clamping - Bidir it's great but very slow - I have 4096 MiB de Vram and I want to cry.

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Dade
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by Dade » Tue Jan 28, 2020 3:07 pm

Noah_ wrote:
Tue Jan 28, 2020 12:35 pm
Dade wrote:
Tue Jan 28, 2020 9:23 am
Noah_ wrote:
Tue Jan 28, 2020 3:48 am
1. Is this rendering method suitable for animation? :?
There have been reports of caustic intensity variations in animations. I have never been able to replicate this problem. But in any case, it is a bug, not an intrinsic limit of the method.
This worries me in a way because I see a lot of potential in this for animations.

Is it still working to resolve this error or does it have to do with the hardware of certain computers?
I just need a test scene that shows the problem (here, in a viable amount of time) so I can investigate/fix what is going on.
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juangea
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by juangea » Tue Jan 28, 2020 8:30 pm

I jump to that wagon, one of the most important things we do is animation, so coherence between frames is very important.

As for an example scene, maybe @lacilaci can share the scene he present here, it's flickering a lot.

viewtopic.php?f=4&t=1688&start=20

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Dade
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by Dade » Tue Jan 28, 2020 11:08 pm

juangea wrote:
Tue Jan 28, 2020 8:30 pm
I jump to that wagon, one of the most important things we do is animation, so coherence between frames is very important.

As for an example scene, maybe @lacilaci can share the scene he present here, it's flickering a lot.

viewtopic.php?f=4&t=1688&start=20
Env. cache has no relation with Hybrid Back/Forward path tracing :?:

P.S. and I must admit I don't see any flickering in this one: viewtopic.php?f=4&t=1688&start=10#p19307 :?:
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Sharlybg
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by Sharlybg » Wed Jan 29, 2020 8:41 am

P.S. and I must admit I don't see any flickering in this one: viewtopic.php?f=4&t=1688&start=10#p19307
same here.

but it is probably this one :

https://streamable.com/d30uq

But maybe this was already fixed i haven't really follow this thread well.
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juangea
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by juangea » Wed Jan 29, 2020 8:46 am

Yes, that one.

Sorry I did not realize this was just about caustics, I was referring to flicker in general when using GI Cache or Env Cache, not just caustics cache :)

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Dade
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by Dade » Wed Jan 29, 2020 10:02 am

Sharlybg wrote:
Wed Jan 29, 2020 8:41 am
P.S. and I must admit I don't see any flickering in this one: viewtopic.php?f=4&t=1688&start=10#p19307
same here.

but it is probably this one :

https://streamable.com/d30uq

But maybe this was already fixed i haven't really follow this thread well.
This is should have been done before exposing in Blender the support for persistent cache :idea: It should work fine with persistent cache.
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juangea
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Re: More than one question (Hybrid Back/Forward path tracing)

Post by juangea » Wed Jan 29, 2020 10:40 am

Does persistent cache takes into account time?

I mean, can it use the persistent information to increase the data for frame 2 using the data from frame 1? or can it interpolate if we calculate persistent data for frame 1,5 and 10, can it interpolate and use persistent data to extrapolate or accelerate render for frames 2,3,4,6,7,8,9?

I would like to know how it works for animation :)

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