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I'm having trouble with cast shadows

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Jeremy Garchow
I'm having trouble with cast shadows
on Jul 25, 2014 at 4:49:05 pm

I have the angles and shadows figured out in a way that is making sense.

What I can't figure out is that a certain shadow is going over the subject. I have a hard time with trying to figure out Ae's 3D composting sometimes, and this is one of them.

Basically, I have a green screened foreground, a background plate. The plate is of a model walking down the runway, the foreground is of a model sitting in a chair, and she is supposed to look like she's sitting on the runway and she is tracked in to the background plate. I am trying to cast shadows of the chair on to the floor of the runway.

To do this, I have a white solid at the "same perspective" as the runway which is a 3D layer and is set to accept shadows. The keyed model in the chair is also a 3D layer, but it is not accepting lights, it is casting shadows. I need to use two lights to get what I want.

The problem is, one of the lights is over the top of the model's foot. I tried masking the shadow layer, but it's too fuzzy, I can't think of a way of adding a new instance of the foot on top without destroying the relationship of everything else in the comp.

Perhaps I am thinking about this incorrectly.

What it looks like:




Comp:





Jeremy


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Dave LaRonde
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 5:04:34 pm

How about animating a garbage matte around the problem area, then moving it above the offending shadow?

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 5:27:17 pm

[Dave LaRonde] "How about animating a garbage matte around the problem area, then moving it above the offending shadow?"

Thanks for the response.

I've tried that, but the matte is too fuzzy.

It ends up looking like this:



I probably built the composite all wrong in the first place, I am just moonlighting as an Ae artist for a few weeks.


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Dave LaRonde
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 6:08:03 pm
Last Edited By Dave LaRonde on Jul 25, 2014 at 6:18:13 pm

I don't know about fuzzy, but I do see an opacity issue in the chroma key -- there's a visible line through the foot.

If you're using Keylight, take a look at your key in the Status view. The transparency should be black, opacity white, and areas like edges that are intended to be semi-transparent will be gray. A green tinge indicates a loss of spill suppression in that area.

I the feeling the foot you're showing us is gray in that view.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 6:20:45 pm

[Dave LaRonde] "I don't know about fuzzy, but I do see an opacity issue in the chroma key -- there's a vuisisble line through the foot."

That's the shadow, hence my problem.

I assure you it's not the key. The footage is flat (or grey) as it's shot log and it's only roughly color corrected.

here's the transparency:



The matte I made is masking the actual shadow layer, not the key. That's why it's fuzzy.

I can't mask the key layer, because it doesn't do anything because the shadow is cast on that layer as well. The keyed layer is a 3D layer. I need 3D to it can pick up the lights and cast the shadows. It's hard to explain.

I might have to "paste" a 2D foot on top and try to track that in, but it seems unnecessary.


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Dave LaRonde
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 8:59:17 pm

Do you need to have the layer with the lady & chair accept shadows? If not, turn it off.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 9:06:41 pm

It is off. Only casts shadows is on. She is somehow casting a shadow on herself.


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Dave LaRonde
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 11:38:03 pm

Well, in that tight screen grab it still looks to me that you have a case of a semi-transparent foot, and the shadow's showing through it.

Without screen grabs of your workspace, it's tough to know for sure.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Jul 25, 2014 at 11:54:46 pm

Screengrab of the comp is in the first post.

You're seeing the shadow on the foot. The picture of the transparent key is when I solo the layer. It is not the key, the foot is rotoed.

It has to do with the placement of the floor in relation to the chair and I can't figure it out.

I'm sure it's my less than stellar compositing skills.


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Walter Soyka
Re: I'm having trouble with cast shadows
on Jul 28, 2014 at 10:36:09 am

When compositing in 3D in Ae, layer order doesn't matter. The fact that you have FashionShow_Key as the top layer doesn't mean it will appear on top of all other 3D elements in the composite if something else is closer to the camera in 3D space -- in this case, your shadow-catcher.

If you don't have any other 3D interactions going on, you might just duplicate the FashionShow_Key layer, turn off its shadow options on the top-most layer, and add a 2D adjustment layer right below it (above the original and the rest of the 3D scene, to break 3D interactions with the other layers). This will keep the 3D positioning of the keyed layer but let it sit on top. You might need just a touch of choke to keep the edges clean.

Alternately, you may be able to get sharper shadows with masking if you increase the shadow map resolution (Comp Settings > Advanced > Options).

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Jul 30, 2014 at 1:36:57 pm

Thanks so much, Walter.

I couldn't figure out a way to get a new instance of the key on top without shadows and keeping the 3D positioning.

This may just work.

Cheers.


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Walter Soyka
Re: I'm having trouble with cast shadows
on Jul 30, 2014 at 2:39:53 pm

[Jeremy Garchow] "Thanks so much, Walter. I couldn't figure out a way to get a new instance of the key on top without shadows and keeping the 3D positioning. This may just work. Cheers."

You're welcome.

Another option might be to use the FashionShow_Key layer as a track matte for the shadow catcher.

Move the shadow catcher directly below the FashionShow_Key layer in the timeline, then enable its track matte as "Alpha Inverted Matte." This will turn off the visibility for Fashion_Show_Key; turn it back on. This should prevent the shadows from overlapping the key layer.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Jul 30, 2014 at 3:31:36 pm

I think I tried that, but the shadow catcher is a white solid that is multiplied.

I'll give it a go, though.


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Aug 4, 2014 at 3:33:51 pm

[Walter Soyka] "If you don't have any other 3D interactions going on, you might just duplicate the FashionShow_Key layer, turn off its shadow options on the top-most layer, and add a 2D adjustment layer right below it (above the original and the rest of the 3D scene, to break 3D interactions with the other layers). This will keep the 3D positioning of the keyed layer but let it sit on top. You might need just a touch of choke to keep the edges clean."

I owe you one. This worked.


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Walter Soyka
Re: I'm having trouble with cast shadows
on Aug 4, 2014 at 8:12:57 pm

[Jeremy Garchow] "This worked."

Happy to help.

With respect to our other conversation, I'm now defining compositing as is one third controlling shades of gray, one third blending them, and one third cheating left and right.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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Jeremy Garchow
Re: I'm having trouble with cast shadows
on Aug 4, 2014 at 11:36:30 pm

[Walter Soyka] "With respect to our other conversation, I'm now defining compositing as is one third controlling shades of gray, one third blending them, and one third cheating left and right."

Ha! Nice one.


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