Multiple meshlights

[Slobodan]

Just wondering,

why one mesh light renders so fast and 9 of them takes forever?

I have a scene with 9 simple spheres just to test different lightning and that thing seems to take forever to get anywhere. If I do it with only one it flies through the scene like it's nothing.

Thanks,

Slobodan

[OnoSendai]

Can u post an image of the scene?
What version?
what settings? (bidir?)

[Slobodan]

Hi Ono,

yes, i'll post an image as soon as I get home.

It's 0.7 test 5 MLT , no BIDiR

I found that scene with multiple mesh lights needs great amount of level correction to brighten it up.
I'll post images and might be clearer then.

thanks,

Slobodan

[Slobodan]

Ok here are the pictures,

They are the same only one has one mesh light and the other 9 of them.
tone map : reinhard pre:1 post:1 burn:6

Both pictures were cooked for 1 hour.

Thanks,

Slobodan

[mrCarnivore]

I think the problem is the tonemapping. Because there are so many bright object in the image with the 9 lights, tonemapping makes the darker parts nearly black.
Turn reinhard off (swithc to linear) or save an igi and use violet for tonemapping.

[Wedge]

Maybe it is slow because of the mirror showing the nine making it more like eighteen? And also the shiny blue ball that shows all of the lights as well.

That's the best I can say.

[mrCarnivore]

I think you are just confusing slow with black... The last picture seem just as grainy as the first to me. The first one just is darker.

Check the tonemapping issue!

[Slobodan]

mrCarnivore,

So, what are you saying is that even with the same reinhard settings two images can be different?? I wasn't aware of that.

I don't agree that noise is the same. I ajusted level in photoshop and they don't look the same. Nine mesh lights look noiser.

I know that in other renderers (Mental ray, Vray) amount of lights matters, I'm not sure if that's the case with Indigo?

thanks,

Slobodan

[mrCarnivore]

The whole point of tonemapping is that two different images have the same overall brightness and dynamic with the same tonemapping settings...

This automatically leads to the effect, that areas that have the same absolute brightness in the original render image have a different brightness in the tonemapped image.

[Kram1032]

Actually, if there are more lightsources, indigo has to calculate more directions of light!
This automatically causes increased render times, except there is very much indirect lighting!
In this case, more lightsources may mean less render time, as the pic need much less photones to get lit in very indirect lit places!

But this should e the same in every renderer.

[Slobodan]

Ok, so i'm confused now, is it more render time or less render time??

[Kram1032]

It normally means more render time, I also guess so for this image, but if there is much indirect lit parts (long corners, edges, curves...), then, the whole scene needs to be lit up by photons, that are bouncing many many times... -> Darker, noisier -> more Rendertime

But in this case, as told, you don't have to care about that... I think it's pretty much lit directly
especialy there, where you've got many lightsources!
So, in this case, more rendertime

[Slobodan]

Thank guys for trying here..

If I read correctly what Kram is saying than single mesh light should have more trouble lighting this room then 9 of them.

I was just wondering if this is normal behaviour for Indigo.

Thanks
Slobodan

[Kram1032]

? No, you didn't read correctly...
reversed

[Slobodan]

LOL this good one....

Well Kram I just thought that more direct light less time??

Thanks,