LuxCore multipass composite

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Egert_Kanep
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LuxCore multipass composite

Post by Egert_Kanep » Mon Nov 04, 2019 10:13 pm

Here is just an overview of what to do with LuxCore aov's. I call aov beauty image that is sum of the passes and combined pass is render beauty.

Caustics can be extracted with subtracting aov beauty from combined (render beauty). This intorduces negative values, but if extracted caustics now added to aov beauty, which has those bright fireflies, it evens them out and you get indentical result as combined. Makes sense, but this isn't a good thing I think. There seems to be some caustics, but majority of caustic contribution is missing from aov's
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combined
combined
aov beauty
aov beauty
caustics
caustics
caustics + aov beauty
caustics + aov beauty
Last edited by Egert_Kanep on Mon Nov 04, 2019 11:20 pm, edited 2 times in total.

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Dade
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Re: LuxCore multipass composite

Post by Dade » Mon Nov 04, 2019 10:35 pm

There is a trick you can use if you want an image with only caustics: use PATHCPU and set balance between light paths and eye paths all in favor of light paths (i.e. 0.0).
You can use the same trick to get an eye paths only rendering by using a value of 1.0.
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Egert_Kanep
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Re: LuxCore multipass composite

Post by Egert_Kanep » Mon Nov 04, 2019 11:07 pm

Okay, that's also good to know. My concern is that when I'm doing multipass compositing, I wan't to avoid ''hacks'' like subtracting and making negative values, because then my image breaks when I start tweaking individual aov's. Everything should be comped in additive.

There is a workaround, where I could keep separated caustics as individual image and then build a second node tree and add it as an extra pass. This would keep the additive workflow.

Thise fireflies appear in direct glossy aov.

I disabled light tracing and aov beauty and render beauty look different. This is bad news for me, I would expect them to be identical
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beauty_comparison.jpg

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Re: LuxCore multipass composite

Post by Dade » Tue Nov 05, 2019 9:42 am

Egert_Kanep wrote:
Mon Nov 04, 2019 11:07 pm
I disabled light tracing and aov beauty and render beauty look different. This is bad news for me, I would expect them to be identical
You have lost me, I don't know how to map some of your term in my LuxCore nomenclature.

Anyway, this is what I mean. This is a rendering with "0.0" (aka only caustics):

caustic.jpg

and this is a rendering of the same scene with "1.0" (aka everything-but-caustics):

nocaustic.jpg

if you sum the 2 images (note: sum, not blend/mix), the result is the complete rendering:

total.jpg

Isn't what you are looking for ?
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Egert_Kanep
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Re: LuxCore multipass composite

Post by Egert_Kanep » Tue Nov 05, 2019 10:26 am

I am trying to rebuild beauty using LuxCore aov's. but the result does not match with the result that is combined by render engine.
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Re: LuxCore multipass composite

Post by Dade » Tue Nov 05, 2019 11:06 am

Egert_Kanep wrote:
Tue Nov 05, 2019 10:26 am
I am trying to rebuild beauty using LuxCore aov's. but the result does not match with the result that is combined by render engine.
Ok, now I get it however, by composing all of them, you should get only this:

Image

The light tracing part is not included in any AOV.

So you should get the correct complete result if you sum:

- direct diffuse
- direct glossy
- indirect diffuse
- indirect glossy
- indirect specular

_and_

- light tracing output:

Image

If you disable light tracing, your original procedure should work fine but caustics are likely to look bad because path tracing alone is really bad at rendering them.
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Re: LuxCore multipass composite

Post by Egert_Kanep » Tue Nov 05, 2019 12:01 pm

Beauty combined from aov's has some much brighter pixels. I'mt trying to figure out why I cannot get identical result to beauty that is coming from render.

This is just opencl render without light tracing
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aov beauty left and render beauty right
aov beauty left and render beauty right

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Re: LuxCore multipass composite

Post by Egert_Kanep » Tue Nov 05, 2019 12:55 pm

Thanks B.Y.O.B for pointing out the clamping. This was the culprit behind my confusion. Clamping is not applied to aov's so I got those bright pixel, now everything makes sense

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Re: LuxCore multipass composite

Post by Dade » Tue Nov 05, 2019 1:56 pm

Egert_Kanep wrote:
Tue Nov 05, 2019 12:55 pm
Thanks B.Y.O.B for pointing out the clamping. This was the culprit behind my confusion. Clamping is not applied to aov's so I got those bright pixel, now everything makes sense
This may be considered a bug, is it :?:
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Re: LuxCore multipass composite

Post by Egert_Kanep » Tue Nov 05, 2019 2:09 pm

Well sort of. One would assume aov's to have same settings applied as beauty render

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