Comping refractions elements in fusion/nuke

[DPS]

How do you correctly composite glass and keep control of the various elements that contribute to the final result?

I did a render using 'affect all channels' for refractions. But I'm getting a double up in my refractions (or all of the othere passes depending how you look at it.

One option is to change refraction to 'colour only' but then I loose control over all of the objects behind the glass.

Hope that makes sense....

Cheers

Dave

[pg1]

Makes perfect sense.
Affect all channels puts the refraction in all channels so when you put the refraction on top it doubles.
I haven't tried this but maybe subtract the refraction from the comp before you add the refraction back over.
i.e you should have something like GI + Light + Reflect - Refract then ADD the refraction on top (with colour correction or whatever it is that you want to do)

[DPS]

If I do:

Lighting + GI + reflection + spec

With refraction set to affect all channels then it doesn't reproduce the beauty render.

If I set refractions to color only and also + refractions then it produces the beauty...

[sharktacos]

If I do:

Lighting + GI + reflection + spec

With refraction set to affect all channels then it doesn't reproduce the beauty render.

If I set refractions to color only and also + refractions then it produces the beauty...

That's odd. With refraction set to "affect all channels" I get the beauty render with lighting + GI + reflection + spec (no need to add refraction). Do you have "affect shadows" on for the refraction?

[svetlozar.draganov]

The usage of the Refraction Render element in the composition depends from the status of the Affect Channels option under the Refraction layer.

If all refractive materials in the scene have Affect All Channels option then Refraction RE should not be used in the composition since its contribution is already distributed across other render elements.
In case where all refractive materials are set to Color Only or Color+Alpha, Refraction RT should be used in the compositions since all refractive information is stored in there.

There is one special case where some of the materials in the scene are set to Affect All Channels while others are set to Color Only or Color+Alpha. With this setup part of the refraction information will be spreaded over the render elements while the rest of it will exists only in the Refraction RE so during the composition it is necessary to specify what part should be taken from Refraction RE and what from other REs.

If you still have issues afterwards please attach the scene(including nuke comp and all RE) and we'll try to find out why to composition does not match the Beauty pass.