9 Replies Latest reply on Dec 16, 2012 8:01 AM by 4reelfx

    Camera Tracker

    Last House Productions

      I'm trying to track the movement of an actor using 3D camera tracker and when I have the track points set to show "2D source" I can see that the movements are being tracked perfectly well, however, when I switch to the 3D solved view, all points on the actor disappear and only the background points remain. Is there a way to parent a null to one of the points visible only in the 2D source view?

        • 1. Re: Camera Tracker
          lasvideo Level 4

          Im going to hazard a guess that you are experiencing a scale related issue that make the trackers disappear due to the interpreted scale of the solve.

           

          Andrew Kramer describes a way to calibrate the tracking data in terms of scale and a ground plane that I think may solve your problem. I know this was a big problem for me using 3D Camera Tracker solves until I learned this technique.

           

          http://www.videocopilot.net/tutorial/3d_truck_compositing/

          • 2. Re: Camera Tracker
            Rick Gerard Adobe Community Professional & MVP

            The tracker points change with time. If the actor is a major component of the scene and the background is relatively plain sometimes the solve is often wrong. It's hard to give you some advice without at least a screenshot.

            • 3. Re: Camera Tracker
              Last House Productions Level 1

              The 2d track points are all there. Is there any way to parent a null to a 2d track point? I know the obvious choice might be to just use the track motion function but it's not clinging to any of the points I specify.  

              • 4. Re: Camera Tracker
                Rick Gerard Adobe Community Professional & MVP

                If you point to keyframes they have to track the keyframe values. Whether this is through an expression or by parenting to a null, there's no way around it. I think that you're assuming that the 3D Camera Tracker is setting keyframes for the layers. It is not. The 3D camera tracker creates keyframes for the camera. You can drop any 3D layer in your scene and if you have a good track the object will look like it is in the scene.

                 

                A screenshot of your problem would really help. Seeing the video you are trying to track would help even more. If a shot will track then the system works. If the shot won't track, it won't.  You may run the tracker without throwing any errors or warnings but the track may be no good. The only way to tell is to look at the way the tracker points lock to the shot when you have created your camera. There are some shots that even the best 3rd party camera trackers can't solve. There are some shots that solve perfectly for a few frames then the solution falls apart.

                 

                Have you done something like this? It's my 1 minute tracking tutorial. It shows exactly what to do to attach text or solids to a track.

                 

                • 5. Re: Camera Tracker
                  Last House Productions Level 1

                  Thanks for taking the time to reply. I'm aware that the camera tracker is used to create a 3d Camera that matches the movement of the footage, but I can see on the 2d source view that it is also tracking the subject.

                   

                  What I'm trying to do is attach something to the body of the actor which I have been unsuccessful in doing with the motion tracker so I thought maybe there was a way to parent a null to one of the points the 3d tracker picked up on the body of the actor.

                   

                  It sounds like this is not an option.

                  • 6. Re: Camera Tracker
                    Todd_Kopriva Level 8

                    That's what mocha-AE is good for.

                     

                    http://forums.adobe.com/message/3856481

                    • 7. Re: Camera Tracker
                      lasvideo Level 4

                      LHP, be sure to do some tutorials on Mocha since there are definite procedures you need to follow depending on if you are tracking an object as opposed to creating a corner pin track. Its not quite as straight forward as using the AE Camera Tracker.

                       

                      http://www.imagineersystems.com/support/training

                      • 8. Re: Camera Tracker
                        Rick Gerard Adobe Community Professional & MVP

                        If the actor is moving in the scene and the background is also moving then there an error between the 3D camera tracking of the actor and the background. Therefore, even using expressions to reverse engineer the camera movement (not easy but doable) is not an option because the actor is moving in the 3D scene. All you get with 3D camera tracking, with any 3D camera tracking, is a best guess solution to the movement of the camera. Other movement in the scene, like trying to 3D track a camera moving through a crowded sidewalk, just adds complexity and introduces tracking errors.

                         

                        Mocha is a good solution to track the actor. AE's tracker may also be a good solution depending on the shot.

                         

                        Again.. just a screenshot or better yet a few frames of your shot on YouTube would go a long way to getting you the easiest workable solution.

                        • 9. Re: Camera Tracker
                          4reelfx

                          Hi I totally understand your issue. I recently had a happy accident, I thought I would just run a 3d camera track and well as it was a locked off camera nothing happened, but when I pulled down the 2d solve option... the tracker markers were locked the best I have ever seen! So I naturally tried to use them and all I could do was delete them.... I was rather annoyed because I wanted to track a new logo onto a moving character in the shot and these markers worked so well but you cant access them! How foolish??

                           

                          Any help will be appreciated.