log fire: strange blobs of light in raw GI

[KenTankerous]

These weird blobs of light show up in the raw GI, and they are very visible in the RGB. Can anyone tell me which settings affect this?

I can post jpegs if anyone needs to see what I'm talking about.

As always, thanks

[Ivaylo Katev]

I can post jpegs if anyone needs to see what I'm talking about.

would be helpful

[KenTankerous]

Okay here it is, thanks for looking.

would be helpful

[KenTankerous]

Ok, I have just conducted a really really long test with a cell size of 0.2cm, I wanted to see if it was about the resolution.

I end up with the blotches again. They're a bit smaller and there are more of them closer together, but still it looks like there's a disco ball in the room. Here's a jpeg of it.

Doing this simulation took a really long time. Eventually max locked up. I was able to recreate the scene and use the .aur files for this render. But these small cell sizes seem to be way too heavy to be useful in production.

[Ivaylo Katev]

looks like the GI settings are to blame. in my oppinion the lighting of area relatively away from the fire by GI is hopeless, the additional lights have ot be used in one or other way. try to make it in two passes and compositing: 1. use the lights with disabled rendering of the simulator, this should produce only the ligh. 2. the fire only.

[jacksc02]

Ken, what GI settings are you using?
Also what "lights" settings are you using in phoenix?

[vlado]

You can also put a rectange VRayLight in "portal" mode right in front of the fireplace; it will help to distribute the GI more evenly without additional lights.

Best regards,
Vlado

[KenTankerous]

Yes I had thought of doing it in passes. Perhaps that's the way to get this done. Thanks, I'll look into it.

edit: this is in reply to Ivaylo's reply.

"looks like the GI settings are to blame. in my oppinion the lighting of area relatively away from the fire by GI is hopeless, the additional lights have ot be used in one or other way. try to make it in two passes and compositing: 1. use the lights with disabled rendering of the simulator, this should produce only the ligh. 2. the fire only."

[KenTankerous]

Hi Chris, I'm using IR map set to Medium for the primary, simply because brute force looked terrible, a bunch of over bright dots everywhere. brute force seems to work well in the secondary, usually I use light cache for my secondary but it looked terrible too, and it even says in the docs that PHX FD doesn't like light cache.

Ken, what GI settings are you using?
Also what "lights" settings are you using in phoenix?

[KenTankerous]

Ah! I had forgotten about that. Yes I should try that. Maybe I could even go back to using brute force for my primary? Thanks Vlado, I will post my results.

You can also put a rectange VRayLight in "portal" mode right in front of the fireplace; it will help to distribute the GI more evenly without additional lights.

Best regards,
Vlado