Chroma Key Experts? at DVinfo.net

Michael Cox · March 6th, 2009, 11:55 PM

Hello,

I have a question about the Chroma Key set-up.
I want to build a set that looks like a picture window in an office building . Easy right?... My question is can I do it with a 90* corner in it? If you can imagine it would look like a big glass corner in a high rise building. Will this work? Or will the image distort or look obviously fake when it makes the bend?

I hope I explained it right.

Thanks in advance.

John C. Plunkett · March 9th, 2009, 09:32 AM

You shouldn't have a problem with the background image bending unless you're trying to create a background using two separate images. I personally think your greatest challenge will be replicating the daylight cast through the window, then again I'm not a pro at compositing.

Nathan Moody · March 9th, 2009, 02:19 PM

Seems like you should position yourself in a similar place and shoot some reference shots to get an idea what your background plates should look like for the composite; this will determine your needs for a background element and how it will need to look. If it's a corner building then if it's in a city, the buildings on the other side of the intersection may be far enough away that your background plate can just be flat, ditto if you'll just be compositing a sky in there. Just get some parallax going if you move your camera and it can look fairly realistic. If I were using After Effects or Nuke, I'd set that layer up in 3D for much easier parallax. If your camera won't be moving, all the easier.

It also depends how much your camera will move and how you block your shots. You'll probably also need to double up on your lights so each part of the right-angle greenscreen is lit as evenly as possible...OR, if you can make it big enough, just make a big flat greenscreen and put it far enough away from your set that it won't need to bend, but there again you'll need to increase your light sources. You could REALLY go guerilla and block your shots so you only look out of some of the windows all of the time, but your shooting plan may not allow for this.

Ger Griffin · March 10th, 2009, 12:54 AM

I think it might not work until you can create the glass in front of the background look by whatever means neccessary. Light reflections, a bit of glare etc maybe even the odd scratch. And then another one for the other panel. As Nathan said, try to get yourself into a similar situation in real life and examine the look of the glass for designing your layers.
Also the thicker the glass the more distorted the image outside it, and these glass panels are very thick.

March 6th, 2009, 11:55 PM	#1
Michael Cox Regular Crew Join Date: Jan 2009 Location: Phoenix AZ Posts: 31	Chroma Key Experts? Hello, I have a question about the Chroma Key set-up. I want to build a set that looks like a picture window in an office building . Easy right?... My question is can I do it with a 90* corner in it? If you can imagine it would look like a big glass corner in a high rise building. Will this work? Or will the image distort or look obviously fake when it makes the bend? I hope I explained it right. Thanks in advance.

March 9th, 2009, 09:32 AM	#2
John C. Plunkett Regular Crew Join Date: Aug 2007 Location: Jacksonville, Illinois Posts: 130	You shouldn't have a problem with the background image bending unless you're trying to create a background using two separate images. I personally think your greatest challenge will be replicating the daylight cast through the window, then again I'm not a pro at compositing.

March 9th, 2009, 02:19 PM	#3
Nathan Moody Regular Crew Join Date: Feb 2009 Location: SF Bay Area, CA, USA Posts: 78	Seems like you should position yourself in a similar place and shoot some reference shots to get an idea what your background plates should look like for the composite; this will determine your needs for a background element and how it will need to look. If it's a corner building then if it's in a city, the buildings on the other side of the intersection may be far enough away that your background plate can just be flat, ditto if you'll just be compositing a sky in there. Just get some parallax going if you move your camera and it can look fairly realistic. If I were using After Effects or Nuke, I'd set that layer up in 3D for much easier parallax. If your camera won't be moving, all the easier. It also depends how much your camera will move and how you block your shots. You'll probably also need to double up on your lights so each part of the right-angle greenscreen is lit as evenly as possible...OR, if you can make it big enough, just make a big flat greenscreen and put it far enough away from your set that it won't need to bend, but there again you'll need to increase your light sources. You could REALLY go guerilla and block your shots so you only look out of some of the windows all of the time, but your shooting plan may not allow for this.

March 10th, 2009, 12:54 AM	#4
Ger Griffin Major Player Join Date: May 2007 Location: Ireland Posts: 579	I think it might not work until you can create the glass in front of the background look by whatever means neccessary. Light reflections, a bit of glare etc maybe even the odd scratch. And then another one for the other panel. As Nathan said, try to get yourself into a similar situation in real life and examine the look of the glass for designing your layers. Also the thicker the glass the more distorted the image outside it, and these glass panels are very thick.