Author Topic: Masking foreground and background elements  (Read 791 times)

2021-01-20, 02:08:32

jiggedyjiggedy

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I'm hoping someone can help me with this issue. It seems like it might be really straightforward, but my brain just can't it right.

I have some emitters that are emitting some "sequins", which then dynamically fall from above and land on the ground. I also have a cylinder as a gold award as the main focus of the scene. In order to get the sparkly reflections from the sequins, the only way I could make it work was to rotate the hydra lighting very quickly in all directions so that the light was constantly catching on the particles as they fall. The problem is this then also affects the lighting and reflections on the gold disc.

So what I'd like to do is render the sequins and the gold disc separately and comp them in AE afterwards. Normally not a problem, but as there are sequins both in front and behind of the award disc, I want to be able to render the sequins, but masking out any that fall behind the award so that I can simply put the solo award layer behind the sequins in AE.

I hope I've explained that correctly. Is there a simple way to achieve this? I have tried with object masking but haven't had any success.

Many thanks!

2021-01-20, 14:48:38
Reply #1

burnin

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Well, since it boggles your mind it'd be nice to make it easy on others posting an exemplary scene file or at least some images of 'have'/'want'.

Well anyway, I imagine you could:
- generate a 'Medal' mask to cut out 'sequins' in the back later.
- make a use of "takes" and/or "multi-passes". Render twice. One set for 'sequins' other for 'Medal'. Compose...

« Last Edit: 2021-01-20, 15:04:15 by burnin »

2021-01-20, 23:41:25
Reply #2

BigAl3D

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Seems like you can have a Sequins-only light by going to the Light's Include/Exclude tab, setting to Include and dragging your particle group into it. Now you can set that light to be as strong and animated as you want. You could also add a Corona Compositing tag set to not cast shadows if it conflicts with your main lighting.

Hard to say for sure without see what your scene looks like.

2021-01-21, 12:13:01
Reply #3

burnin

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True,  posted the same for 3rd option, but then removed it since I presumed, OP is implying the use of HDRI - 'hydra lighting'(?).
As I tried few possible techniques and its feature set combinations: using HDR images on Corona Lights, C4D lights, geometry w/ Light Mtls & Sky Objects (last two w/o Include/Exclude options)  it's all a 'no go'.

'Light linking' or "Project" C4D's Light feature with IBL/HDRIs is simply out of reach given Corona's (for C4D) current state.

Edit: Maybe I'm missing something, but Image Based Light Linking is also a "no-go" with C4D's engines.
« Last Edit: 2021-01-21, 12:25:54 by burnin »

2021-01-21, 18:21:45
Reply #4

BigAl3D

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Yeah, I don't know what "hydra lighting" is either. I'm going to test an idea for this and post back. Also, yes, you can create a C4D material and add an HDR to the Luminance Channel, then drag that onto a sky object or any a TV screen as an example.

2021-01-21, 22:25:54
Reply #5

BigAl3D

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Well, I tried some of my ideas out and didn't get the results I was hoping for. For now I think the two render method is the way to go.

2021-01-27, 14:47:59
Reply #6

maru

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@jiggedyjiggedy - if you could explain your setup a bit better, that would definitely help. Viewport screenshots, examples renders, that kind of stuff. If you can't share those things, maybe at least a schematic drawing in MS Paint. :)
Right now it's hard to tell what exactly you are seeking - is it HDRI / enviro lighting, or some kind of spotlight,...?