3 Replies Latest reply on Dec 8, 2015 12:27 PM by blaxh404

    Tracking chroma key

    blaxh404

      Hi everyone !

      I'm asking this question here because i have a big issue, it's been weeks now and i can't solve it.

      I have shot this scene with a canon mark II with magic lantern in raw.

      IMG_9392.JPG

      I wanted to do camera tracking to then import it in cinema 4D to integrate the guy in a full 3D environment.

      I was not able to find another method than this one so i made these orange marks on the screen so the 3D camera tracker marks can attach to it. The issue appears at the end of the tracking, it says "Analysis solve failed".

      The first time i tested it, it was not shot in raw and there was only soft natural light but it worked ! I have seen the common problems, the camera is not too shaky and i think there is enough points (maybe the issue is here but i can't really add more points).

      Do you have a solution? Maybe another way to do it?

      Hope everything is clear, don't hesitate to ask me questions.

      Thank you very much !

        • 1. Re: Tracking chroma key
          Mylenium Most Valuable Participant

          AE's 3D tracker needs sufficient motion, which in your shot isn't existing. You need to use alternate tools that allow manual placment of reference markers.

           

          Mylenium

          • 2. Re: Tracking chroma key
            Rick Gerard Adobe Community Professional & MVP

            I think you approach is flawed. Plain square tracking markers with no detail (they look like post it notes) don't really provide very much information for tracking. If you are going to use something like post it notes have some printed with a checkerboard or some kind of pattern on them. I'm assuming your actors motion is limited to the area not covered by the green screen. Insufficient camera movement and a small amount of detail in the scene with little perspective change plus an actor that is moving around can cause analysis failure.

             

            Including the background and light stands is a good start. If you can't get the analysis to solve by selecting all of the tracing markers that attach to your actor and deleting them or by using a technique I will describe later, you may have to reshoot. If you can to shoot again get rid of the post it notes and put something at the edges of your action area that is 3D and approximately on the same plane where you want to put your new 3D object. This will put some geometry in the shot that the Camera Tracker can use to analyze the camera movement. Even cardboard boxes with printed labels like these stacked on either side of the action would give you something to camera track.

            corrugated-paper-fruit-boxes-1482042.jpg

            The more detailed geometry you have to track the better your chances for success.

             

            To try and save this shot you might also want to try masking out the actor and most of the green screen like this:

             

            Then pre-compose moving all attributes and run camera tracker again. If you can get a successful camera track you can then simply replace the pre-comp with the original footage or turn off the mask in the pre-comp. I've done this many times on shots that would not track.

            Screen Shot 2015-12-08 at 8.11.28 AM.png

            For example, Take this shot for example. The actress walks in from screen right and the camera follows her as she bends down to show us her knee. It would not camera track because she took up way too much of the scene and the fog in the background kept the camera tracker from picking out details in the back wall:

            Screen Shot 2015-12-08 at 8.22.08 AM.png

            We wanted so add an animated set piece behind the actress and just in front of the wall so I added a mask like this.

            Screen Shot 2015-12-08 at 8.21.38 AM.png

            I then pre-composed and then Camera tracked. Then the mask was set to none so I could see the entire scene and I added a solid and a camera to the back wall so some more set pieces could be added to the scene.

            Screen Shot 2015-12-08 at 8.20.55 AM.png

            Today we will do the roto so the set piece can pass behind her and complete the shot. This was a lot easier and faster than going through and deleting tracking markers by hand.

             

            Just one more note. I noticed in your shot that there was a lot of lens distortion from the wide angle lens. AE's camera does not have lens distortion. It would be a good idea to shoot a grid with your camera exactly square to the grid and figure out what you need to do to correct the lens distortion before you try and build your virtual set. If you like the distorted look you can always put it back in later. The shots that I posted have been processed to remove all distortion before anything else is done. It's the only real way to make 3D camera tracking work perfectly across the whole frame.

            • 3. Re: Tracking chroma key
              blaxh404 Level 1

              Thank you very much for your answer rick, i'm going to check all these things and hopefully i will figure out. Thanks again !