OT: Video Chroma Keying - Green Screen

[tomasino]

Hey just checking with the knowledge base.

Doing a music video shoot.
Yes, track is still in the process of being Recorded, Mixed and Mastered in SawStudio. :cool:

Does anybody here have any experience doing green screen/chroma key work (setup & processing).

I got the green screen and did a test shoot and a post render with some success.
Just have to tighten up details of the entire process.. that's all! :rolleyes:



Maybe should switch to a blue screen considering the target content.
Am considering chroma keying off a non RGB base color. Which no doubt, sounds crazy.
Need to light the screen separate from the target content. Kinds of lights?
Rendering seems to take 3 - 4 times as long as it usually does. Is normal?


Beyond that, I can already tell there's an unlimited number of ways to approach the shoot and the post work.
Kinda like a real complicated audio mix.. but with video and colors.

Any input from the knowledge base would be appreciated.
Thanks n' as always you guys rock! :cool:

[cgrafx]

Hey just checking with the knowledge base.

Doing a music video shoot.
Yes, track is still in the process of being Recorded, Mixed and Mastered in SawStudio. :cool:

Does anybody here have any experience doing green screen/chroma key work (setup & processing).

I got the green screen and did a test shoot and a post render with some success.
Just have to tighten up details of the entire process.. that's all! :rolleyes:



Maybe should switch to a blue screen considering the target content.
Am considering chroma keying off a non RGB base color. Which no doubt, sounds crazy.
Need to light the screen separate from the target content. Kinds of lights?
Rendering seems to take 3 - 4 times as long as it usually does. Is normal?


Beyond that, I can already tell there's an unlimited number of ways to approach the shoot and the post work.
Kinda like a real complicated audio mix.. but with video and colors.

Any input from the knowledge base would be appreciated.
Thanks n' as always you guys rock! :cool:

There are a few things to pay attention to.

1. Yes the the green screen should be lit separately from the target content.
- if you can get them, get some fluorescent video lights (flolights, Kino Flo, etc)
- I use three FloLight FL-330's (6-bulb fixtures) to light the 20ft wide green screen at our studio (FL-330 (http://www.flolight.com/fluorescent-lighting/fl-330aw-6-x-55w-fluorescent-video-light-with-wireless-dimming-and-free-lamps.html))
- I use another four FL-220's (4-bulb fixture) to light the actors.

2. Try to light the green screen as evenly as possible.

3. Do not over light the green screen (this will help to reduce spill). Too much light on the screen will just make keying harder as it will spill onto everything and make it more difficult to pull a clean key.

4. Keep your actors or live content as far away from the green screen as possible (this will also reduce spill).
- I try to keep at least 10 feet between the screen and the actors/content when shooting. More is better if you have room and a large enough screen to manage it.

5. IMPORTANT. Make sure you shoot with a camera that can do at least 4:2:2 color. Anything less will make pulling a decent key very hard and general result in ugly jagged edged keys. The resolution of the color content is simply to low to key from.

6. You can use Red, Green or Blue to key from. Any other color will be pulling color from a mixed color source and will likely not work very well.
- The sensor in the camera is either a BAYER single chip sensor (which will has the greatest resolution on the green channel) or 3-chip RGB sensor. Again pulling from a single channel is going to give you the best results.

[tomasino]

There are a few things to pay attention to.

1. Yes the the green screen should be lit separately from the target content.
- if you can get them, get some fluorescent video lights (flolights, Kino Flo, etc)
- I use three FloLight FL-330's (6-bulb fixtures) to light the 20ft wide green screen at our studio (FL-330 (http://www.flolight.com/fluorescent-lighting/fl-330aw-6-x-55w-fluorescent-video-light-with-wireless-dimming-and-free-lamps.html))
- I use another four FL-220's (4-bulb fixture) to light the actors.

2. Try to light the green screen as evenly as possible.

3. Do not over light the green screen (this will help to reduce spill). Too much light on the screen will just make keying harder as it will spill onto everything and make it more difficult to pull a clean key.

4. Keep your actors or live content as far away from the green screen as possible (this will also reduce spill).
- I try to keep at least 10 feet between the screen and the actors/content when shooting. More is better if you have room and a large enough screen to manage it.

5. IMPORTANT. Make sure you shoot with a camera that can do at least 4:2:2 color. Anything less will make pulling a decent key very hard and general result in ugly jagged edged keys. The resolution of the color content is simply to low to key from.

6. You can use Red, Green or Blue to key from. Any other color will be pulling color from a mixed color source and will likely not work very well.
- The sensor in the camera is either a BAYER single chip sensor (which will has the greatest resolution on the green channel) or 3-chip RGB sensor. Again pulling from a single channel is going to give you the best results.

Thanks!

Definitely gonna get some new lighting. Will give the ones you mentioned a hard look.

Besides tons of stuff on Amazon, found this place: Tubetape (http://www.tubetape.net/servlet/StoreFront)

Will adjust the positioning relative to the screen. Was way too close.

Did a test trying to key off of another color. Like you said.. it didn't work at all.

I'm using GoPro cameras.. not sure about the chip sensor but the CineForm codec definitely calls out 4:2:2. I'll investigate this further.. maybe time for a new camera!

[cgrafx]

Thanks!

Definitely gonna get some new lighting. Will give the ones you mentioned a hard look.

Besides tons of stuff on Amazon, found this place: Tubetape (http://www.tubetape.net/servlet/StoreFront)

Will adjust the positioning relative to the screen. Was way too close.

Did a test trying to key off of another color. Like you said.. it didn't work at all.

I'm using GoPro cameras.. not sure about the chip sensor but the CineForm codec definitely calls out 4:2:2. I'll investigate this further.. maybe time for a new camera!

Lots of places also rent this stuff (lights & cameras), they can even ship it to you.

[Mike Bizanovich]

All great info from Phillip G. I would say though that you can get very good keys without 4:2:2, but it is easier. We use Canon 7Ds all the time with very good results. Light the background evenly and not too bright. If it's a cloth screen, use stretchers to get it as flat as you can. Use shallow(er) depth-of-field to smooth out a rough background.

We use Red Giant Primatte Keyer. Great results. Not free, but very powerful.

Lots of great videos out there on techniques, etc. Take a look at some of them then play a lot.

[tomasino]

All great info from Phillip G. I would say though that you can get very good keys without 4:2:2, but it is easier. We use Canon 7Ds all the time with very good results. Light the background evenly and not too bright. If it's a cloth screen, use stretchers to get it as flat as you can. Use shallow(er) depth-of-field to smooth out a rough background.

We use Red Giant Primatte Keyer. Great results. Not free, but very powerful.

Lots of great videos out there on techniques, etc. Take a look at some of them then play a lot.
Groovy guys, thanks!

Yea, it's cloth.. 10' x 20'. Washed it, ironed it and rolled it up instead of folding it a kabillion times.. (next time will let the pro's do it!).
It's way flatter now, but still gonna stretch it as much as possible (as recommended).
Next, I work on the lights.

For a camera, I think I'm leaning towards a Sony (like the A77) mostly 'cuz it writes an MP4.. like the GoPro (fits my processing work flow).
It has the Exmor™ APS HD CMOS Sensor.. still trying to figure out if it's a single chip or a 3 chip. Will probably work fine either way.

Thanks for the tip on RedGiant Primatte Keyer.
Heavy stuff.