ugly grain

[Fabrice]

Hy all

I'm rendering a ceiling-light.
But with irr map set to veryhigh (3h on a bixeon 3 Ghz )
the image is very "granulous".
Especialy on the ceiling...

Note : there is no light, only an open box surrounding (for the walls) and an hdri environnement (for daylight).



Please tell me the magic setting I miss...[/img]

[flipside]

Can you show a bit more of the scene?

Why use a hdri for an interior lighting?

So it's just a self illuminating material these lights?

[Fabrice]

>Why use a hdri for an interior lighting?
The walls are open on a side.
I use it to obtain some light color variations ... but I'm not sure about effiency of this choice.
>So it's just a self illuminating material these lights?
Yep. Mtl Wrapper with "generate gi on 3.
>Can you show a bit more of the scene?
Sure !

oooooh ugly isn't it ?

[flipside]

Can you share the scene for testing?

I don't understand how all that light can get on the celing with that aluminium case in between lights and ceiling.

I agree that a hdri isn't the most efficient way to get light in an interior, just to have some color variation. I think you would better use some large vray plane lights with slightly different colors. That would give you nice shodows and you can lower your ir map settings a lot because the area shadows make up for 90% the lighting.

wouter

[Fabrice]

>I don't understand how all that light can get on the celing with that aluminium case in between lights and ceiling.
There are 2 other neon lights above the case (=between case and ceiling).

>the area shadows make up for 90% the lighting.
What do you mean by this ?

I think I'll try with a big lighten plane...[/quote]

[flipside]

These shadows will cover up GI artifacts from your lamps on the celing for example.

Now you rely purely on GI quality, while using area lights, you get nice shadows even with low GI settings.

[Fabrice]

Ok. Your right.
But the purpose is to show how this lamp provide light...so I can't "put" shadow where light has to be.
I'm affraid I have to rely on GI but I'll post the next test that seems to be better...

Lot thanks for your advices Flipside !

[Fabrice]

I'm about getting a result :
- I hide the noise on the ceiling by raising "interp samples" to 200
- I replaced the 2 upper neons (with "mtl wrapper") by a VRay light.
- Fine tuned the mats...
- backlight is still hdri
- with this setup I can render on "high" instead of "very high"... 30 mn instead of 3h30 !


[/img]

[flipside]

Looking good!

Set it to custom and play with the values a bit more, don't relay on the presets only (keep in mind the presets are tuned for 640*480 resolution!).