Corona Renderer Forum

Corona Renderer for Cinema 4D => Corona Renderer for Cinema 4D - general => Topic started by: atin on 2020-03-25, 11:47:35

Title: Alpha / Transparent Background with shadows
Post by: atin on 2020-03-25, 11:47:35
Hi all!

Subject:
I want to render out a knob animation in png frames for a free UI project. Attached you see the final rendering.
The Knob + lights are in a Null-Object Group and the grey background a single plane with a hole.

Problem:
I can't get it how to have only the knob + lights visible and the grey backround transparnet (alpha)

Question:
How I have to (step by step) set the scene/settings up that the knob + lights are visible only (with shadows) & the grey bg is not visible / transparent?

Thanks & stay healthy! :)


Title: Re: Alpha / Transparent Background with shadows
Post by: beanzvision on 2020-03-25, 13:35:18
Hi, Is this what you are trying to do? If so, in the material go to "Advanced" and change the alpha mode to "always black". I hope that helps.
Title: Re: Alpha / Transparent Background with shadows
Post by: atin on 2020-03-25, 13:58:53
Thanks for reply,

Ok maybe I wrote not clear enough - attached what I want as the goal.

So, the picture has 3 main elements:

1. knob with shadow
2. lights
3. grey background

My goal is to render out DIRECT a png file where the original grey background (3.) does not exist No further Photoshop should be required. In the attachement is a png. So, if you would have some new red background, you would see the new red background behind the knob & lights (attachment "bg-example").

The lights & the knob with the shadow (1+2) have to be still fully visible.

Again: Render out a totally normal png file (Knob, Shadows, Lights), only without the grey background of my first post, no further Photoshop actions should be required, just a png with transparency.
Title: Re: Alpha / Transparent Background with shadows
Post by: atin on 2020-03-27, 08:30:07
Nobody a solution?
... or is this not possible?
Title: Re: Alpha / Transparent Background with shadows
Post by: romullus on 2020-03-27, 10:57:02
It is possible. You need to use shadowcatcher for the background and set its alpha mode to "for composite". Then save the render to png or tiff with alpha. See attached example. Is this what you're after?
Title: Re: Alpha / Transparent Background with shadows
Post by: iacdxb on 2020-03-28, 21:02:15
Thanks Romullus, png work fine, just transperant object with shadow.

But with PSD multi-pass, floor is not transparant same as png... any idea...?

Thanks.
...
Title: Re: Alpha / Transparent Background with shadows
Post by: romullus on 2020-03-28, 21:09:05
Sorry, i'm not familiar with PSD.
Title: Re: Alpha / Transparent Background with shadows
Post by: iacdxb on 2020-03-28, 21:24:51
psd is with other multi-passes layered file....!
May be two saves, one psd layered and one png.

Anyone else who can see this with psd it comes or not...?

Thanks.
...
Title: Re: Alpha / Transparent Background with shadows
Post by: burnin on 2020-03-29, 00:00:17
PSD with alpha channel works fine.
How do you save your PSD? As an Image, Single- or Multi-Pass?
Title: Re: Alpha / Transparent Background with shadows
Post by: iacdxb on 2020-03-29, 05:14:56
@Burnin, saves with Multi-pass layers.
floor applied with shadow catcher... shows black.

...
Title: Re: Alpha / Transparent Background with shadows
Post by: burnin on 2020-03-30, 01:11:37
Well, shadow catcher alpha can be either solid, transparent or for compositing...
;)
Title: Re: Alpha / Transparent Background with shadows
Post by: iacdxb on 2020-03-30, 05:19:40
Hi Dev team,

I hope you can help me more in this.
I tried shadow catcher different alpha modes... but transparent background non of them works with psd...!
Only png works.

Anyway to get transparent background with multi-pass....?

Thanks.
...





Title: Re: Alpha / Transparent Background with shadows
Post by: romullus on 2020-03-30, 09:33:07
Does it save alpha channel with PSD? If so, you need to apply mask to layers of interest. If alpha channel is not saved, then you need to save it separately, import it into PSD and apply the mask.
Title: Re: Alpha / Transparent Background with shadows
Post by: iacdxb on 2020-03-30, 13:13:03
shadow catcher, set alpha mode to compositing.. and floor comes black....
in this way... two saves, one png for transparent background and second normal psd.
and then place png in psd multi-pass file and play....!

any way to get solid ground...?

Thanks.
...
Title: Re: Alpha / Transparent Background with shadows
Post by: atin on 2020-04-02, 11:47:04
It is possible. You need to use shadowcatcher for the background and set its alpha mode to "for composite". Then save the render to png or tiff with alpha. See attached example. Is this what you're after?

Awesome, thats it, problem solved.... it was exactly what I searched for!

Thank you very much!