Jump to content


Photo

framing for CGI compositiing and lighting green screen


  • Please log in to reply
3 replies to this topic

#1 Scottie Mei

Scottie Mei
  • Basic Members
  • PipPip
  • 35 posts
  • Cinematographer

Posted 10 November 2006 - 11:06 PM

Hi, I am shooting a music video using green screen and CGI compositing. I am shooting S-16mm with 1.85 aspect ratio. The shot is 3 actors walk in frame from the bottom frame right over the lower letterbox area (not the actual 1.85 frame) and climb up to the 1.85 picture area (shooting a spaceship door for plate). We will build a platform (6' height) for actors to climb up and My first question is how am I going to set the framing precisely since the height of the platform has to be right at the bottom edge of the 1.85 frame. I am planning using trasparency paper taped over my monitor for framing, but the actual green screen space might not giving me enough width. I wonder can I shoot those actor in real size and zoom out the image at post as long as have enough height in the picture area for them to climb up? Then, I know the green screen has to be lit evenly, but since the actors will climb up the platform (also painted in green) which might cast shadow on the platform. Is it going to be a problem at post to key off the platform? If so, how am I going to light the platform without compromising the lighting? The actors will be lit with back key as the door opens. I am shooting in a week. :( Please help me out!! Thanks.


A frustrated cinematographer
  • 0

#2 Will Earl

Will Earl
  • Basic Members
  • PipPipPipPip
  • 385 posts
  • Other
  • Wellington, NZ

Posted 11 November 2006 - 12:26 AM

the actual green screen space might not giving me enough width.


Green screens often don't cover the whole frame of a shot. Garbage and travelling mattes are often used to extract non-greenscreen elements from shots. Keep the greenscreen behind elements that are normally difficult or time consuming to roto out - which in your case would be the action of the actors.

Then, I know the green screen has to be lit evenly, but since the actors will climb up the platform (also painted in green) which might cast shadow on the platform. Is it going to be a problem at post to key off the platform?
If so, how am I going to light the platform without compromising the lighting? The actors will be lit with back key as the door opens.


Ground interaction with greenscreen is still quite a difficult thing to pull off convincingly - even through most keyers can handle shadows reasonably well. Is there any reason why it needs to be a CG platform? Can it not be a real setpiece?

Talk with whomever is doing the VFX on this music video, most of these problems can be effectively solved by a bit of good ol' commucation.
  • 0

#3 Ken Minehan

Ken Minehan
  • Basic Members
  • PipPipPip
  • 168 posts
  • Cinematographer
  • Singapore

Posted 13 November 2006 - 03:49 AM

Hi, I am shooting a music video using green screen and CGI compositing. I am shooting S-16mm with 1.85 aspect ratio. The shot is 3 actors walk in frame from the bottom frame right over the lower letterbox area (not the actual 1.85 frame) and climb up to the 1.85 picture area (shooting a spaceship door for plate). We will build a platform (6' height) for actors to climb up and My first question is how am I going to set the framing precisely since the height of the platform has to be right at the bottom edge of the 1.85 frame. I am planning using trasparency paper taped over my monitor for framing, but the actual green screen space might not giving me enough width. I wonder can I shoot those actor in real size and zoom out the image at post as long as have enough height in the picture area for them to climb up? Then, I know the green screen has to be lit evenly, but since the actors will climb up the platform (also painted in green) which might cast shadow on the platform. Is it going to be a problem at post to key off the platform? If so, how am I going to light the platform without compromising the lighting? The actors will be lit with back key as the door opens. I am shooting in a week. :( Please help me out!! Thanks.
A frustrated cinematographer


Hello, you sound like you have an very fun job coming up. Shooting everything against green can be tricky sometimes, but talking to your animator will help alot. If your animator can come on set to advise you from time to time may get you out of trouble later too. I recently shot a TV commercial where the scene was 8 people sitting at a boardroom table having a meeting. We shot this behind a green screen. The table they were sitting was also green screen. In this situation the actors were intereacting with the green table in front of them so it was quite difficult to avoid all spills.

Is your platform goin got animate and morph into something else? Is there a need for it to be green screened? I would advise you to build the platform in to your set if you can. By doing this, you can avoid the problem of green spills, and also save your animator alot time in post.

I also had shadows on the table, but thats a minor problem as they can key out twice if need be. This is of course not the ideal situation but it can easily be solved.
Make sure to have tracking points in the back ground and fore ground for your animator if you are intending to have your camera moving.

Another thing my animator asked me to do, is to avoid shallow depth. For example, if an actor in the foreground is in focus and another actor in the back ground is blurred, it creates a problem for the guy doing the keying out. He told me to shoot as sharp and big depth as possible, and that he will blur the back ground after in post.

Just make sure to use this week before your shoot to have several meetings with your animator. it's also a good time to be clear on what your comped back ground is going to look like too.

I hope i have been helpful. Would love to see your MTV once it's done.
regards and good luck.
Ken Minehan
  • 0

#4 Scottie Mei

Scottie Mei
  • Basic Members
  • PipPip
  • 35 posts
  • Cinematographer

Posted 14 November 2006 - 01:19 AM

Hey Ken,
Thanks so much for the great info. I am meeting with my animator this weekend. hopefully, we will figure soemthing out. Thanks a lot and have a great week.

Scott


Hello, you sound like you have an very fun job coming up. Shooting everything against green can be tricky sometimes, but talking to your animator will help alot. If your animator can come on set to advise you from time to time may get you out of trouble later too. I recently shot a TV commercial where the scene was 8 people sitting at a boardroom table having a meeting. We shot this behind a green screen. The table they were sitting was also green screen. In this situation the actors were intereacting with the green table in front of them so it was quite difficult to avoid all spills.

Is your platform goin got animate and morph into something else? Is there a need for it to be green screened? I would advise you to build the platform in to your set if you can. By doing this, you can avoid the problem of green spills, and also save your animator alot time in post.

I also had shadows on the table, but thats a minor problem as they can key out twice if need be. This is of course not the ideal situation but it can easily be solved.
Make sure to have tracking points in the back ground and fore ground for your animator if you are intending to have your camera moving.

Another thing my animator asked me to do, is to avoid shallow depth. For example, if an actor in the foreground is in focus and another actor in the back ground is blurred, it creates a problem for the guy doing the keying out. He told me to shoot as sharp and big depth as possible, and that he will blur the back ground after in post.

Just make sure to use this week before your shoot to have several meetings with your animator. it's also a good time to be clear on what your comped back ground is going to look like too.

I hope i have been helpful. Would love to see your MTV once it's done.
regards and good luck.
Ken Minehan


  • 0


Gamma Ray Digital Inc

Glidecam

Paralinx LLC

Metropolis Post

Wooden Camera

Aerial Filmworks

rebotnix Technologies

Abel Cine

The Slider

Visual Products

CineLab

Opal

Media Blackout - Custom Cables and AKS

Tai Audio

Rig Wheels Passport

Broadcast Solutions Inc

CineTape

FJS International, LLC

Technodolly

Willys Widgets

Ritter Battery

Broadcast Solutions Inc

Gamma Ray Digital Inc

rebotnix Technologies

Tai Audio

Paralinx LLC

Glidecam

Willys Widgets

Aerial Filmworks

Visual Products

CineLab

Metropolis Post

CineTape

Opal

Wooden Camera

Technodolly

Ritter Battery

FJS International, LLC

Media Blackout - Custom Cables and AKS

The Slider

Rig Wheels Passport

Abel Cine