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Greenscreen + window


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#1 Cedric Larvoire

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Posted 10 April 2006 - 05:23 AM

Hello everybody,

I've been doing some research about having a greenscreen behind a window. I got some useful information, but i would need some details :)

Here's the thing, we are shooting a viral for a fast-food restaurant. The scene is about two people eating their meal in front of this big window, and things happening outside. There are four differents scenes for now (four virals, four *weird* things happening outside the window). And we want the actions of the two people eating to be exactly the same.

So we are planing on shooting them on a greenscreen in a studio, and then shoot what's happening outside on location. The thing I'm particularly worried about is the reflection of the two people in the window, cause they are sitting really close to it, and it's night outside.

Considering the window *is* our framing (we don't see the borders) , it has to look good. If we have the window in the studio, how can we key the reflection ? as it's see-through, we are gonna see the greenscreen behind.
And if we have the window on location only (or no window), without the reflection of the people, it's just gonna look like there is noting... and look weird :)

do you have any idea to save us ? :)
thank you ;)

PS : we are shooting hdv, xl h1 ...
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#2 Keith Mottram

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Posted 10 April 2006 - 08:28 AM

do you have any idea to save us ? :)
thank you ;)

PS : we are shooting hdv, xl h1 ...


An idea that will save you is- not shoot on hdv. blunt but serious. you can key and keep reflections, but you will need a clean greensceen to pull, a good compositor, proper software and an uncompressed source. otherwise it will look like you've 'keyed it'. if you can only afford to shoot on hdv, i'd suggest test with your fx team and work on the best post look to 'cover up' all the artefacts that keying highly compressed footage will give you.

keith
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#3 Michael Nash

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Posted 10 April 2006 - 11:01 PM

There are some compositing systems that can deal with semi-transparent subjects, but as noted the quality of the original recording is all-important.

Generally for keying semi-transparent subjects such as smoke (or in this case reflections), I always recommend a luminance key instead of color. But this isn't always practical, and may not be in your case.

Is there any way to set up another camera opposite the window to capture the reverse angle of the actors, to be used a source for layering in a reflection? Perhaps using green screen, a garbage-matte out the extra camera.
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#4 Cedric Larvoire

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Posted 12 April 2006 - 10:30 AM

Hi everyone. and thanks for your participation ! ;)

So, after a couple of tests with the fx team, we are not gonna have any actual window on set. And we will fake the reflection in post.

We realised that, it doesn't matter that much to have a good reflection of the people in the window. A small camera covering the other side will do the trick. It's more important to have some lights (fake) reflecting to have the illusion that a window is here.

thanks again ;)

PS : will try to post some captures when we are done.
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#5 Bob Hayes

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Posted 12 April 2006 - 05:31 PM

I'd say go with reflections. They would really be there. Try making the green screen slightly higher key then normal may thin out the reflections.
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#6 Mark Allen

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Posted 12 April 2006 - 05:40 PM

I am coming to this late, but being someone who does has done a crazy amount of Greenscreen stuff I will say... those reflection that you'll capture live on the set of the actors are what will sell your shot. They key just fine in any real keying application. Without them, the BG will look like a cut out.

There are two ways to fake it. 1. shrink down your live image and put them in the window - sometimes people won't realize for a quick shot that they are not really seeing a reflection. Don't recommend it though. The other is to shoot a reverse of the actor's from the window's perspective immitating their exact motions. Don't recommend that either.

HDV is going to be not fun to key at all.
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#7 Chandra M.Mouli

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Posted 13 April 2006 - 12:11 AM

I am coming to this late, but being someone who does has done a crazy amount of Greenscreen stuff I will say... those reflection that you'll capture live on the set of the actors are what will sell your shot. They key just fine in any real keying application. Without them, the BG will look like a cut out.

There are two ways to fake it. 1. shrink down your live image and put them in the window - sometimes people won't realize for a quick shot that they are not really seeing a reflection. Don't recommend it though. The other is to shoot a reverse of the actor's from the window's perspective immitating their exact motions. Don't recommend that either.

HDV is going to be not fun to key at all.


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#8 mark preston

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Posted 25 June 2006 - 04:44 PM

I am new to this forum and to greenscreen but soon to be walking the path with a train. Just wondering with all the compression of HDV and keying, if you convert the HDV footage to Targa files or something simliar, will that not stop the problems of GOPs and problems....or have i just completely missed the point?
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