Alpha Channels for individual objects? Tweet

[Pauls]

Hi....still very new to Octane and can't seem to find a solution. Maybe it's right before my eyes and I don't see it.

I'm trying to make an object have it's own alpha channel. I can use the material ID layer but I never really get a clean selection from that in Photoshop. Close but not real crisp. I'd love to be able to turn all black and only the one I want white. Any way to do that?

Also, how can I completely turn off an object from rendering. I can turn it's opacity to '0' but the shadow still renders and I am unable to select 'through' the '0' opacity object to the object behind. The '0' opacity object seems to still leave behind a 'ghost'.

TIA

[bepeg4d]

Hi,
are you working in Standalone or plugin?
About "Alpha channel for individual objects", please have a look at v2018 with Cryptomatte support here:
viewtopic.php?f=24&t=70809
Latest version can be downloaded here:
viewtopic.php?f=24&t=71406

About hiding objects, the best way is to avoid to load that geometry, unless you have to interact with it.
In this case you can use the Object Layer node/options to hide geometry from camera, and shadows, the way depends from Standalone or specific plugin used.

ciao Beppe

[Pauls]

Thanks.

I'm using Standalone.

I was aware of the 'colored' crypto matte but haven't been able to get it real crisp in comparison to a pure black and white alpha.

[FrankPooleFloating]

If Cryptomatte is not your cup of tea, and you're not finding any other way to isolate your material, you can do this: Make a separate mesh of whatever this material is > do a quick Render Layers setup > give this new mesh a unique ID > enable Layers in Render Target and enter desired ID# > render (with alpha enabled) > open render in PS > CTRL+ALT+D to duplicate into comp PSD > CTRL+Left Click thumbnail of your (isolated render layer) PSD layer > there is your perfect selection, for layer mask (if even needed now) or whatever. However, you do say "object have it's own alpha channel", so maybe you do not even need to make a separate mesh. Just do render layers without the bs about isolating mat as mesh, and you are g-t-g.

[franchais]

I'm guessing the best way to do this is to set each object as a separate render layer, and then render out each object separately?

can be abit loborious if you have a lot of objects

[Taksha]

That would be awesome to use the Render Tag from C4D. Alpha at all works great (with vectron fractals too! Yeah)
But the Render tags with diffrent object levels are ignored.

My work areound is to render again with native engine - all effects, light and shaders off, and its pretty fast to get the channels.
With PS you can make an automatic action to seperate the object channels to get the diffrent masks from the second rendering

cheers