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Additive layer on emitter almost disables it

Posted: Sun Mar 09, 2014 12:31 am
by AlexP
To reproduce:
- add emitter layer
- add 100% additive layer e.g. like glass
- light scene with it and then turn off additive layer
I'll post images to show it on monday.

Re: Additive layer on emitter almost disables it

Posted: Mon Mar 10, 2014 1:36 pm
by AlexP
Here is image, left is normal emitter, right is emitter same with additive layer:
Image

Re: Additive layer on emitter almost disables it

Posted: Mon Mar 10, 2014 7:36 pm
by Mihai
Could you please try this with the latest beta (.6), I can't confirm this. Or please upload that test scene somewhere and post the link.

Re: Additive layer on emitter almost disables it

Posted: Mon Mar 10, 2014 8:49 pm
by AlexP
It's jpg from fire from latest .6 beta, but same with production. Mxs here:
http://www.myam.pl/testy/emitter_test01.mxs
I'm pretty sure it was working fine in v2 as I used a lot such emitters to simulate "milky glass" lamp shades.

Re: Additive layer on emitter almost disables it

Posted: Thu Mar 13, 2014 1:29 pm
by AlexP
Mihai, any news?

Re: Additive layer on emitter almost disables it

Posted: Thu Mar 13, 2014 9:14 pm
by Mihai
I checked the scene now, I would say this is something like a limitation because of the additive fix in V3, but we will try to see if this can be improved. Although in your case, lets say you want to create a milky plastic type material that will be visible when the emitter is off. Create your material as usual, with one additive layer on top. But instead of putting your emitter component in the bottom Layer, put it in the top Layer - problem solved.

Re: Additive layer on emitter almost disables it

Posted: Thu Mar 13, 2014 9:55 pm
by AlexP
Doh, indeed reversing is simple solution in that case. Thank you!
For me most problematic was not dimming but very noisy emitter causing fireflies.
Best regs.

Re: Additive layer on emitter almost disables it

Posted: Thu Mar 13, 2014 11:02 pm
by Bubbaloo
But if the additive layer is weighted, it will affect the emitter strength. I would just simply add a new additive 100% layer on top of the stack with only an emitter in it.

Re: Additive layer on emitter almost disables it

Posted: Fri Mar 14, 2014 12:53 am
by numerobis
i'm not sure if i understand the problem and how the material should look like... but why would i use an additive layer at all?
I would just take two BSDFs + emitter in one layer. Or add the emitter with a new layer but using normal blending and not additive.
What is the advantage of using additive emitters?

Re: Additive layer on emitter almost disables it

Posted: Fri Mar 14, 2014 4:29 am
by Mihai
Addtive emitters is not the issue, but you want to use additive layers when working with plastic type materials. So you can't get away from addtive mode.

Re: Additive layer on emitter almost disables it

Posted: Fri Mar 14, 2014 4:40 pm
by Bubbaloo
numerobis wrote:why would i use an additive layer at all?
I would just take two BSDFs + emitter in one layer. Or add the emitter with a new layer but using normal blending
Then, when the emitter is off, the underlying material will be black instead of the desired look.

Re: Additive layer on emitter almost disables it

Posted: Fri Mar 14, 2014 4:54 pm
by Bubbaloo
Example:
Image

Re: Additive layer on emitter almost disables it

Posted: Fri Mar 14, 2014 5:33 pm
by Mihai
But that's just because you set the top layer to normal blending and set it to essentially be a "black" emitter. Since it's set to normal blending, anything underneath this layer won't be visible, unless you start lowering the layers opacity/weight.

You CAN put both the emitter component and two BSDFs in one layer (as numerobis asked), to have a plastic like material that doesn't use any additive layers. When you turn off or lower the intensity using Multilight, it will start to reveal the two BSDFs. But in AlexP case, he still wanted to use Additive layers and in that case you should put the emitter component either in this additive layer, or on its own in a third layer, also set to additive.

Image

EDIT:

This part: "Or add the emitter with a new layer but using normal blending and not additive." will of course turn the material black when you turn the emitter off, like Brian showed.

But this part: "I would just take two BSDFs + emitter in one layer" will reveal the BSDFs when the emitter is off as the screenshots above show.

Again, plastics tend to look better using Additive mode, and in V3 you no longer have to worry about using too many additive layers, which in itself is an extremely important fix.

Re: Additive layer on emitter almost disables it

Posted: Fri Mar 14, 2014 5:39 pm
by numerobis
yes...
i meant this:
Image

or this:
Image


edit: too slow...

I normally avoid additives when possible, but if there is really no difference in v3 concerning speed and noise compared to 1 layer will give them a new try i think...

Re: Additive layer on emitter almost disables it

Posted: Fri Mar 14, 2014 5:43 pm
by Mihai
Your top example is not recommended because then the layer weight of the top layer will also influence how strong the emitter is, which is in the bottom layer.

So:
If you want to use normal blending + emitter, just put the emitter and BSDFs in the same layer
If you want to use additive blending + emitter, for safest use, put the emitter in its own additive layer and make sure it's in the top most additive layer.