Chroma key exterior for bus ride

Daniel Kedem · February 28, 2007

I'm about to shoot a short (10min.) which takes place, almost exclusively, on a bus in motion through an urban area. I'm considering bringing the bus into a studio and having all the exteriors added later via green screen. We will not have the means to block streets, tow a bus, or rig light from outside - and so this seems a good idea. Any ideas on how to make this look good or otherwise good arguments for going outside are welcome.

P.S. bus sequence in 'The Interpreter' is good reference for doing it this way. Obviously o lesser budget and skill :)

Thanks a lot,

Daniel

Will Earl · March 1, 2007

It would be helpful to know if you have a budget or not, and the skill/experience of your crew - mainly your VFX/Post crew.

Daniel Kedem · March 1, 2007

It would be helpful to know if you have a budget or not, and the skill/experience of your crew - mainly your VFX/Post crew.

Budget is restrictive but exists. Numbers won' be useful, as this will be shot in Israel. I think I can get a decent post crew for this.

Will Earl · March 1, 2007

Well there several issues you'll come across, first up is dealing with the bus windows and the greenscreen. Some productions remove the windows to get a clean greenbacking and replace them with CG versions later, even though most colour difference keyers can deal with reflections and transparency. Depends on how comfortable you are with pulling keys with glass or replacing with CG glass later on.

The second issue is camera movement, obviously you probably don't wish to have the camera locked down for every shot, with handheld or pan/tilt shots you can get away with a 2D track later on in post, while a steadicam or tracking shot might require a camera survey and tracking markers on-set to help ease things in post.

The third thing is background plates, you'll need to shoot these to cover all the shots you'll need. You should be able to track these plates onto the windows so you get moving reflections across the windows.

And lastly, interactive light on-set to simulate the movement of the bus. You'll need to figure out what looks right for passing shadows, and travelling highlights.