PhotonGI cache

Discussion related to the LuxCore functionality, implementations and API.
provisory
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Re: PhotonGI cache

Post by provisory » Thu Sep 12, 2019 12:23 pm

Dade wrote:
Thu Sep 12, 2019 7:42 am
I should have fixed the problem...
Thank you!

provisory
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Re: PhotonGI cache

Post by provisory » Fri Sep 13, 2019 9:47 pm

lacilaci wrote:
Wed Sep 11, 2019 4:55 pm
I have this idea that might be a bit stupid but maybe not:

Would it be possible to control after how many bounces is photongi used? Maybe this would help with some reflection artifacting or leaks?

So maybe have 1 or 2 bounces brute force and afterwards sample from cache(a control exposed to the user).

The reason is that sometimes luxcore performs well in interior even without photongi but some areas are a bit "too deep" in terms of gi so they could benefit from photongi. However enabling cache might bring some artifacting even to areas which were ok and fast before. So I have to pick between artifacts and speed...

In my head I think this could help protect areas exposed to few bounces but still give speedup for hard to reach areas.
I like the idea of the control over the number of bounces before using PGI cache.

In the meantime you could try to enable Add Light Tracing with Glossiness Threshold: 1.
According to my tests it helps to illuminate hard to reach areas. After all PGI uses Light Tracing too.
Cons: doesn't work with Matte (but works with Glossy or Disney with max. roughness) and darkens speculars (without PSR)

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lacilaci
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Re: PhotonGI cache

Post by lacilaci » Sat Sep 14, 2019 6:56 am

provisory wrote:
Fri Sep 13, 2019 9:47 pm
lacilaci wrote:
Wed Sep 11, 2019 4:55 pm
I have this idea that might be a bit stupid but maybe not:

Would it be possible to control after how many bounces is photongi used? Maybe this would help with some reflection artifacting or leaks?

So maybe have 1 or 2 bounces brute force and afterwards sample from cache(a control exposed to the user).

The reason is that sometimes luxcore performs well in interior even without photongi but some areas are a bit "too deep" in terms of gi so they could benefit from photongi. However enabling cache might bring some artifacting even to areas which were ok and fast before. So I have to pick between artifacts and speed...

In my head I think this could help protect areas exposed to few bounces but still give speedup for hard to reach areas.
I like the idea of the control over the number of bounces before using PGI cache.

In the meantime you could try to enable Add Light Tracing with Glossiness Threshold: 1.
According to my tests it helps to illuminate hard to reach areas. After all PGI uses Light Tracing too.
Cons: doesn't work with Matte (but works with Glossy or Disney with max. roughness) and darkens speculars (without PSR)
hm, never tried such high threshold..

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lacilaci
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Re: PhotonGI cache

Post by lacilaci » Sun Sep 15, 2019 6:29 am

But it also makes me think.. Isn't it necessary to have lighttracing threshold at 1 so that all materials are included for correct sds with PSR build?

marcatore
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Re: PhotonGI cache

Post by marcatore » Fri Aug 14, 2020 12:09 pm

coming back to PGI...

I have a scene with a glossy wodden floor and curtains with glossy translucent material and they're noiser than the walls and other objects are using matte materials.
I've seen, using the the PGI debug mode "show indirect/path mix" that floor and curtains are red.
I've tried to replicate the room in a simple scene with just one material and I've tried to render (in debug mode) the room as a full glossy room.
I've tried to set the glossiness threshold to have a "blue" render and this is the result compared to a matte material.

glossy material
Image

matte material
Image

Is it normal? Isn't it possible to caching more with glossy materials?

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Dade
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Re: PhotonGI cache

Post by Dade » Fri Aug 14, 2020 12:11 pm

marcatore wrote:
Fri Aug 14, 2020 12:09 pm
Is it normal? Isn't it possible to caching more with glossy materials?
What are you using as glossy roughness and PGI roughness threshold ?
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marcatore
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Re: PhotonGI cache

Post by marcatore » Fri Aug 14, 2020 12:24 pm

Image
higher material roughness value , more red image
as soon as I go little over the PGI glossiness threshold, the image becomes more blue.

Image

If I put the PGI glossiness threshold over the mat roughness, the image becomes (correctly) full red
Image

marcatore
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Re: PhotonGI cache

Post by marcatore » Fri Aug 14, 2020 8:15 pm

another question:

if I launch a final render with border, the PGI calculation is reduced by the area I'm rendering or it's always a full frame calculation?

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Re: PhotonGI cache

Post by marcatore » Sat Aug 15, 2020 6:21 am

another question:
as PGI is a simplified representation of the lighting...is it mandatory to consider also the normal map when the system decides if use PGI or Brute force?

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Dade
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Re: PhotonGI cache

Post by Dade » Sat Aug 15, 2020 10:15 am

marcatore wrote:
Fri Aug 14, 2020 12:24 pm
higher material roughness value , more red image
as soon as I go little over the PGI glossiness threshold, the image becomes more blue.
This is the expected behavior:

- high roughness => nearly diffuse reflection, rays spread in all directions, can hit a near or far object => half way between red and blue.

- low roughness => nearly specular, like a mirror, all rays fired in nearly the same direction, very likely to always hit the same object (and at the same distance) => mostly red or blue (no half way).
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