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Bluescreen & Shadows
Hi
I have alot of bluescreen footage I’m keying and placing in a AE 3d environment. I’ve done this several times but have never come up with a way to solve the problem of casting shadows from keyed footage that has some perspective on the subject.
Take the example of a lion standing in a 3/4 position. By creating a mock shadow [ie: duping the keyed footage, turning it black and feathering, spin the x axis 90 degrees] it is easy to get the front legs to match up but because the back legs are on a different plane they don’t match up.
I use 2 methods to get around this:
01. If I’m not spinning the camera around it too much I sometimes just push the shadow further along the Z axis than is correct and move it a bit if the subject moves. It’s a bit dodgey and never 100% correct but often not detectable
02. I correct the shadow precomp with a meshwarp so it has a common baseline that matches with the footage. This is ok if the subject doesn’t move but a pain if the subject changes position in the shot.
Does anyone have a simple technique or know a tute I should check out? There’s got to be a better way!
Cheers
Danny
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9 Replies
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Won’t a cast shaodw from a light on the object give you the result you are looking for….maybe I am missunderstanding the question… 🙂
Mark
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Lights will cast a shadow but this will have the same effect as trying to match things up with the mock shadow I described ie: because the lion’s back legs are on a different plane in the shot, the shadow cast will only connect with whatever is touching the ground plane.
I don’t think there really is a solution for this. It really comes done to shooting things right on bluescreen from the outset. Unfortunately the director hasn’t done much of this sort of thing.
I’d just like tyo know what everyone else usually does with this type of thing.
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Distort > Corner Pin your duplicated (shadow) footage.
Justin Productions
Tangerin01@hotmail.com
Adobe After Effects 6.5 Professional -
Thanks Justin. That’s pretty much the same as the meshing. However it gets tricky when the subject is moving.
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I hope you’re charging a good rate for all the work you have to do by hand. Producers need to know that fixing on-set mistakes is expensive.
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[Steve Roberts] “Producers need to know that fixing on-set mistakes is expensive.”
Seconded!
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You don’t know the half of it! There’s also the great idea of dollying and tilting without any marks for 3d tracking…yeah, why not….
Fix it in the post hey?Any other ideas on the shadows?
I’m trying to pull long drawn out shadows from the bluescreen but am thinking perhaps shorter [high noon] might be better. That would mean I could cross both sides of the Z axis ie: shadow fore and rear of the subject.
Thanks for all the help.
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Hmmm, I have an idea, but it might not be worth it and I don’t have time to try it out.
Create a solid, and draw a mask on it that is the general shape of the part of your talent that’s having shadow problems.
Now, make it a 3D layer and put it in the proper position behind your subject (as if your subject, in this case a lion? was 3 dimensional and not just a flat layer in 3D space…)
Next, change the Material Options of your solid to Cast Shadows “Only”. This way, you may get a shadow with proper perspective but you won’t see the solid casting the shadow.
I don’t know, you might have to place a layers in space above the subject and behind it. Say, a Top view of the lion’s back, and then a Front view of it’s hind legs. If the shadow doesn’t have to be crisp, you might be able to get away with a very rough mask shape, and not have to animate the mask much.
I have no idea if this would work, but thought I’d give you my brainstorm!
Good luck!
Jon
TreeLine Productions
Fort Collins, CO USACurrently producing these popular podcasts:
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Thanks Jonathan.. that’s a really interesting idea. Might give it a try.
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