PhotonGI cache

[Dade]

But the cause is definitely emission on material as you can see in the screenshots, where it only happens with emission plugged in.

I tried to replicate the setup but doesn't happen here. It may be the BlackBody texture

[lacilaci]

I think it's happening with image texture aswell. Will investigate tomorrow.

[Fox]

I have open world scene setup with no walls to photons bounce around.
Single light from infinite lightsource where float values go up to 1 600 000 000 aka normal gain.
2'th render i use mesh emitter (800 triangles) where also float values go up to 1 600 000 000 aka normal gain for camera to show correctly exposed image.

Caustic Cache, Hemi Infinity, normal gain

Caustic Cache, Hemi Infinity, gain10000

Caustic Cache, Mesh Emitter, normal gain

Caustic Cache, Mesh Emitter, gain10000

Indirect Cache, Hemi Infinity, normal gain

Indirect Cache, Mesh Emitter, normal gain

Caustic Cache, Hemi Infinity, gain10000, GlossinessT 0

Caustic Cache, Hemi Infinity, gain10000, GlossinessT 4294967295

[lacilaci]

I created small isolated case here:

The attachment 00_concept_lux.zip is no longer available

the small selected object with material+emission will completely ruin photongi unless you hide it or unplug emission

emission:

NOemission:

[provisory]

I can't try it now myself, but maybe set the diffuse color of the emitter mesh to black.

[lacilaci]

I can't try it now myself, but maybe set the diffuse color of the emitter mesh to black.

This doesn't change anything.

[provisory]

Then decrease emission's importance.

[Luximage]

Yes you can decrease the emission's importance to 0.01 , also your pendant emission light consists of many faces, if your light was simpler like a plane your cache would be better from the start.

[lacilaci]

importance doesn't solve the bug, it just makes the problem much less apparent with a very weak light. However if you have low importance but strong light, you end up with the same issue. Lowering importance is not even a workaround, it's almost the same as disabling the emission.

[Dade]

I have added the support for automatic indirect cache size. Now, if you set path.photongi.indirect.maxsize to 0, PGI will automatically estimate the cache convergence error and stop when it is under a threshold (default: 5%). There is a new property to set the threshold:

Code: Select all

# Default 5%
path.photongi.indirect.haltthreshold = 0.05

The log output of the process looks like:

Code: Select all

...
[LuxCore][10.364] PhotonGI trace photons thread count: 12
[LuxCore][11.480] PhotonGI additional indirect photon stored: 2276345
[LuxCore][11.480] PhotonGI additional caustic photon stored: 0
[LuxCore][11.480] PhotonGI total photon traced: 2000000
[LuxCore][12.599] PhotonGI additional indirect photon stored: 2276553
[LuxCore][12.599] PhotonGI additional caustic photon stored: 0
[LuxCore][12.599] PhotonGI total photon traced: 4000000
[LuxCore][12.682] PhotonGI estimated current indirect photon error: 329.82%
[LuxCore][13.801] PhotonGI additional indirect photon stored: 2275863
[LuxCore][13.801] PhotonGI additional caustic photon stored: 0
[LuxCore][13.801] PhotonGI total photon traced: 6000000
[LuxCore][13.879] PhotonGI estimated current indirect photon error: 4.32%
[LuxCore][13.879] PhotonGI building radiance photon data
[LuxCore][13.881] PhotonGI filtering radiance photons
...

It will trace more and more photons until when the halt condition is met.

The GUI should offer a combo with 3 settings:

• Preview (error 15%)
• Final render (error 5%)
• Custom (user input error)

It seems to work very well and may speed up the pre-process because it avoids to trace any additional (excessive) amount of photons.