alpha for png

[the ando]

hi guys,
i have rendered few png sequences but forgot to check the alpha Chanel so there is no alpha. is there any way to render only  all the alpha ?
got glass transparency i have to see so mask dont work i have to render the alpha
thanks,
Oren     

[burnin]

must shade then,
in which case your best next thing is to:
- override with most simple material,
- Preserve Glass,
- set GI mode to Single bounce 
and also lit as simple as possible

[the ando]

will try it

[NicolasC]

Hello,

Try CShading_Alpha Render Element + "Render Only Masks" render setting (Scene Tab / General Settings / Render Overrides section).

[burnin]

Ah, yes...  could be w/ 3DS Max.

I was explaining "how to" in C4D.
 

[romullus]

It's not 3ds Max specific thing, it's the same in both host softwares. As CShading_Alpha name suggests, alpha is shading element, so disabling shading will not work. Following Burning's suggestions is a good way to safe some render time, but unfortunately there's no cheap way to render only alpha channel, you still need to render full scene, so next time take extra caution to save every bit of information that you think might be useful.

[NicolasC]

As CShading_Alpha name suggests, alpha is shading element, so disabling shading will not work.

My bad - answered too quickly indeed ;)

[Pedro Torres]

It's not 3ds Max specific thing, it's the same in both host softwares. As CShading_Alpha name suggests, alpha is shading element, so disabling shading will not work. Following Burning's suggestions is a good way to safe some render time, but unfortunately there's no cheap way to render only alpha channel, you still need to render full scene, so next time take extra caution to save every bit of information that you think might be useful.

What if you select everything and add it as a mask?