9 Replies Latest reply on Jul 21, 2008 6:11 AM by (Rammia)

    Chroma key problem

      Hi,
      I am preparing for shooting a film in which I have 7 minutes scene in the car with lots of dialogues so it will be much easier with the green screen. But there lies a problem. Actors are smoking all the time. And that smoke cause me a problem.
      I will probably shoot on HDV but I`ve tested it on DV and used a keylight in After Effects. The result on people satisfied but the smoke doesn`t exist. It`s eaten by keylight.
      Does anyone have a solution? Maybe with different chroma key? It would help me a lot.
      Thanks,
      Rammia
        • 1. Re: Chroma key problem
          Level 1
          It would probably be relatively easy to recreate the smoke in post production compared to trying to capture it agaist a green screen.
          • 2. Re: Chroma key problem
            Ko Maruyama User Group Manager
            I would shoot the smokers smoking.

            Yes, there are ways to simulate a little smoke, but it's difficult, and not always convincing.

            It's difficult to key smoke from green (it basically acts as a diffusion.... painful blurrness), but if you have a camera movement on slowly evolving and accumulating smoke, you'll find it's even harder to get photo-real digital smoke than it is to color correct spill.

            When people move (arm gestures, body movement of any kind) through smoke, it pushes the smoke around in an organic collision that is a bit of nasty when you try to reproduce it without a serious fluid simulator.

            Some things to consider before you take out those cigarettes from the car.

            AND DON'T FORGET... COMPOSITE! You don't have to get the people AND the smoke in a single pass. If the people are clean in one pass, and the smoke is clean in a separate pass, composite the two keying passes together to marry the results.
            • 3. Re: Chroma key problem
              Level 1
              I agree it is impossible to recreate the smoke because it will be a lot of it. In fact, it`s not a smoke from the cigarette but from joint of "marihuana" which is circulating between 3 actors in the car, and it is very important for the story, I can`t take it out.
              And I think it`s impossible to composite too. Any other solution?
              • 4. Re: Chroma key problem
                Ko Maruyama User Group Manager
                Half and Half.

                Key as much as possible, and introduce "filler" smoke when you need. You might want to shoot a little black box of smoke (although it'd be v.v. difficult to wrangle)
                • 5. Re: Chroma key problem
                  Level 1
                  Thanks, but I am not sure yet. I am now testing with dvgarage filter, it is a little bit better but I don`t think it is gonna be convincing.
                  • 6. Re: Chroma key problem
                    Joey Morelli Level 1
                    I know Cigarette smoke can be done nicely in Particular...just don't have it in front of me right now.
                    • 7. Re: Chroma key problem
                      Andrew Yoole MVP & Adobe Community Professional
                      I don't like your chances of pulling a good enough key from either DV or HDV - too much fine detail is lost in both formats.

                      Any chance you could shoot the scene in a better format - perhaps use a camera with an SDI output and a computer that records uncompressed? Or shoot digi-beta/HDCAM?

                      Or the ultimate way - rent a low-level car trailer, tow the car around and shoot it for real.
                      • 8. Re: Chroma key problem
                        Ko Maruyama User Group Manager
                        Andrew's "Ultimate Way" is probably the best solution. Be sure to use prop marijuana.

                        There are plenty of easy-to-mount camera rigs for light cameras
                        • 9. Re: Chroma key problem
                          Level 1
                          I will shoot on DVCProHD. My budget is very, very small so I am thinking about shooting in cabriolet, for real, no green screen, only with sun light and easy-to-mount camera rigs. What do you say about that option?