Alpha !

[BorderLine]

Hi Team,
On thing i prefer in Octane, it's premultiplied alpha who give a very good and precise Alpha.
Here, always blue halo around the leaves !
Pehaps i'm doing something wrong ? Appreciated help !
Thanks

[Lucutus]

Have you tried to use a black direct backround environment yet?

[BorderLine]

Perfect ! Thanks Lucutus

[LukaK]

How do you deal with that in interior renderings, for example when you have glass windows and you want to keep reflections of windows glasses? Because right now I'm rendering beauty shots without window glasses with black direct backround environment, then I must rerender glass objects only with refl. render pass, so I can composite reflections back in Photoshop.
I'd like to keep reflections and internal reflections of double glass, but with this method it's impossible.

[Lucutus]

You can try and use the Refractions Override with pure black too...this should do the job.

[Juraj]

You can try and use the Refractions Override with pure black too...this should do the job.

And this can fuck-up a lot of things in scene :- ) It's very obscure, and not many people know it, but Refractions override, can also affect the reflections and light in the scene because it affects the rays on its last step into the space.
It doesn't work 100perc. identical in way like Direct visibility override, which doesn't affect anything at all, only visibility.

Here's my workaround:

As long as you always use fake (thin) glass for architecture windows, you almost never have to use global refraction override. If you need refraction override for elements with real refraction ( like organic water pitcher, glass, wine bottle, lamp, etc..) add black refraction override through the material.


Also, regarding background and reflections in photoshop:

Know that reflections will only correctly stack up, if you composite them in linear (32bit mode in PS). If you composite in gamma (8bit or 16bit PS mode), there is a trick, select your alpha channel, and change gamma of it through image adjustments :- ) It will brighten up the alpha part of glass and they will show more reflection.
Best way to composite additional reflections from reflections pass is through Linear add in 32bit mode, and Screen in 8/16bit.

[LukaK]

You can try and use the Refractions Override with pure black too...this should do the job.

And this can fuck-up a lot of things in scene :- ) It's very obscure, and not many people know it, but Refractions override, can also affect the reflections and light in the scene because it affects the rays on its last step into the space.
It doesn't work 100perc. identical in way like Direct visibility override, which doesn't affect anything at all, only visibility.

Here's my workaround:

As long as you always use fake (thin) glass for architecture windows, you almost never have to use global refraction override. If you need refraction override for elements with real refraction ( like organic water pitcher, glass, wine bottle, lamp, etc..) add black refraction override through the material.


Also, regarding background and reflections in photoshop:

Know that reflections will only correctly stack up, if you composite them in linear (32bit mode in PS). If you composite in gamma (8bit or 16bit PS mode), there is a trick, select your alpha channel, and change gamma of it through image adjustments :- ) It will brighten up the alpha part of glass and they will show more reflection.
Best way to composite additional reflections from reflections pass is through Linear add in 32bit mode, and Screen in 8/16bit.

Thank you Juraj for your time saving  tips, I'll definitely try next time with thin glass method. Yes, global refraction override isn't good if you have other reflective object in the scene (window seen in mirror for example).

Best regards, Luka

[DarcTheo]

As long as you always use fake (thin) glass for architecture windows, you almost never have to use global refraction override. If you need refraction override for elements with real refraction ( like organic water pitcher, glass, wine bottle, lamp, etc..) add black refraction override through the material.

Is it always better to use thin glass on windows? I've always made sure to go through the models we receive and shell or remake the glass planes thinking it was better to use it with thickness. Do you just lose a refraction pass when using thin glass? I sometimes use refraction pass to help brighten an interior when doing exterior shots if its looking a bit gloomy inside.

sorry slightly off topic.

[Juraj]

As long as you always use fake (thin) glass for architecture windows, you almost never have to use global refraction override. If you need refraction override for elements with real refraction ( like organic water pitcher, glass, wine bottle, lamp, etc..) add black refraction override through the material.

Is it always better to use thin glass on windows? I've always made sure to go through the models we receive and shell or remake the glass planes thinking it was better to use it with thickness. Do you just lose a refraction pass when using thin glass? I sometimes use refraction pass to help brighten an interior when doing exterior shots if its looking a bit gloomy inside.

sorry slightly off topic.

I actually use the thin glass on shelled plane or box :- ) I still get the double-reflection you expect from windows (slight waviness), but no refraction, which is barely visible with the thickness of this glass and curvature.