# Live Feed / Recorded Loops



## arfinator (Jan 28, 2008)

Hello,

My school is putting up a unique version of the show "Wings of Desire", based off of the movie. My directory wants to have "Two different worlds", one in which angels are sitting on something like scaffolding. These angels are then filmed, live, and projected onto like the top of a building.

He wants this all to be seen, so like there is a large projection screen in the rear of our black box theatre and it wants the live image to be superimposed onto the recorded loop of like a building.

We are a very small school and have a very small budget to do what he wants ($1500 for all aspects of the show).

Does anyone have any ideas on how the superimposition would work? Does anyone know of any products that allow this?

Thank you very much in advance.

Regards,

Hess Smith


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## cvanp (Jan 28, 2008)

So you want your angels to be in front of a background, but you can't have the background?

If so - you need chroma key, and then live switching software to process the chroma key. Perhaps http://www.varasoftware.com/products/wirecast/

That might not be fast enough, and I know of no hardware chroma key solutions off the top of my head.

Is that sort of what you're looking for?


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## SHARYNF (Jan 29, 2008)

You would need to rent a video mixer with chroma key ability, the Panasonic MX50 would do the trick and is quite common in rental stock This would allow you to do it live, you need to get a evenly lit background of a typically green or blue background

http://www.studio1productions.com/Articles/KeyEffects.htm

works quite well, takes a bit of practice to get the lighting even, and to get used to how to set it up on the mixer but once you get it is can do what you want to do

Sharyn


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## arfinator (Jan 29, 2008)

Oh. Thank you very much. I will look into this. 

Do you know how much these are to rent on average?

Thank you. 

Regards,
Hess Smith


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## museav (Jan 31, 2008)

I took it that you wanted to have a scene presented live while at the same time those same actors are also superimposed on a projected background. Same actors and movements in two different settings, one live and one virtual. The problem with a basic chromakey for that might be that you would have to have a good chromakey background for the live setting, which might not be practical if that 'set' is also part of the play.


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## kwotipka (Feb 1, 2008)

arfinator said:


> Hello,
> My directory wants to have "Two different worlds", one in which angels are sitting on something like scaffolding. These angels are then filmed, live, and projected onto like the top of a building.



Hum,

An interesting situation. You are going to need some room for the chromakey set. Depending on your available space, can you come up with some senic behind them (ie, paint a flat or canvas with the scene you want) and then just project the whole image onto the screen? Will the background need to change? It may seem like a bit more work but if you are projecting the whole thing anyhow and don't really have a budget, it may be worth looking into. It is also a whole lot technically easier to do.

kw


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## arfinator (Feb 1, 2008)

He keeps changing his mind a lot, so now, I believe he has made it easier on me. He wants the entire set white (which, i am guessing will be a logistics nightmare) and then we are going to use Arkaos software and use the white background as the chroma key and then project the angels onto various locations.

Does that all sound feasible?

On a side note, if I focus gelled lekos and gobos at a large piece of butcher paper that is attached to the grid and to the wall, will it create an interesting effect? I want it to symbolize the lighting of a rock concert and if I used a chase sequence, i think that it might work, without the need of renting actual rock concert lighting.

Thank you very much for your help.

Hess Smith


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## museav (Feb 2, 2008)

I'd stay away from white. Even if you could get it to work, look at what happens when the meteorologist wears a blue or green tie when using blue or green screen, you get the video showing up wherever that color is. Now think of video appearing on anything white in the image such as teeth, eyeballs, etc. Probably not the effect wanted. The key color should be something not found in the live image.


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## arfinator (Feb 2, 2008)

Ooo. OK. I should talk to him about that. I don't think that that would be the effect he wants. 

Thank you so much for mentioning that, we would have ended up noticing it tech week and then stuck with nothing to do.


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## SHARYNF (Feb 3, 2008)

THe MX50's should rent for under 150 dollars, 
What you want to do if you are concerned about the background, is use a BLACK background, light the set and then use LUMA key for the key, thus instead of color it is using light and dark. Can use a white background http://www.videomaker.com/article/9021/



Sharyn


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## kwotipka (Feb 6, 2008)

If you are using white then it is a luma key not a chroma key. In a chroma key you are keying out a color. Technically white is not A color. In any case, there are other issues that you have to deal with a luma key. The first is that your lighting has to be spot on because you are keying based on the luma value of your scene. Sooo if you are dealing with angels (in white) you are going to have a hard time keying out a white background and keeping their wings on. I am guessing a chroma blue because it is a richer color and less luma dependent then green.

I would really look at recording / playback vs. doing this live. Tons of kids today have camcorders and FCP so the cost / hassle of doing this once and posting it might outweigh the cost / hassle of live.

Came across this on a job the other day. These guys had one of these rigs and they were doing this Karoke meets VH1 where they put the heads of the people singing on these cheezy cartoon bodies that were dancing.

**** pricey though:

http://www.new-media.com.au/Datavideo-DVK100-Chromakeyer-pr-1891.html

kw


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## SHARYNF (Feb 6, 2008)

This is why I would suggest using BLACK as the background if you need to do a luma key, getting an even black background is a bit easier. danger of course is that if anything on the "angels" is black it will disappear so hair etc you need to be careful 
Chroma key is great because you typically do not have the key color in the image, but takes a bit more skill. 

Sharyn


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## ruinexplorer (Apr 24, 2008)

Make sure you allow yourself plenty of time to play with the chroma-key. The pitfalls you will run into is the distance between your talent and the background (to minimize shadows) as well as even lighting on the talent and the background. Ask your local tv station if you can come in and look at the set for the weather guy.


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