3 Replies Latest reply on Jun 6, 2016 2:32 AM by armoose

    Motion Tracking help

    armoose Level 1

      Hi, firstly thanks to everyone in this forum. I had some trouble motion tracking this shot.



      So I want to have the screen come off the computer  and stick to her hand like its literally stuck to her hand.


      What I've done: I basically masked the image before her hand comes into frame then Roto'd her hand and composited the two. I made the new maksed 'screen' 3d.  I just need some guidance on when she moves her hand from palm facing the screen to palm facing the audience and then places the her hand in her purse. The complication is when she moves her hand. How do I get this 'screen' to mimic her hand movements with the least amount of jitter on the part of the screen. How would I go about motion tracking this shot?


      This is the first time Ive done this complicated of an effect. So I am eager to not give up. Let me know if anyone has any suggestions. Thanks in advance.




        • 1. Re: Motion Tracking help
          Rick Gerard Adobe Community Professional & MVP

          After Effects does not have a 3D motion tracker so you have to fake it by tracking planes and using corner pin tracking. It's probably going to involve a lot of hand tweaking and is probably best accomplished using Mocha. You would establish the back of her hand as a plane then use corner pin to simulate the 3d. As here hand swings in front of her body and the screen rotates you are going to have to do some hand key framing. The trick with this kind of move is to not use too many keyframes.


          Another approach would be to Motion Track her thumb and index finger to get scale and rotation values. Get the best track you can and then manually reposition the trackers every 10 or so frames until things follow along fairly well. You will want to cut up the shot into sections so you can use as much automatic tracking as you can. Apply these values to a 2D null, parent the replacement null to the screen and get the best track you can. When you have a null or a bunch of nulls tracking the hand with rotation and scale convert all the nulls and the screen to 3D layers and start animating the rotation values of the screen using as few keyframes as possible.


          On the other hand you might be better off key framing the corner pin by hand and keeping everything 2D. It all depends on how smooth the shot is. The trick is to use as few keyframes as possible. You might also what to add something to the screen when it attaches to her hand like a glow and exposure effect. Something like this:

          Screen Shot 2016-06-05 at 7.42.23 AM.png

          Screen Shot 2016-06-05 at 7.42.31 AM.png

          Screen Shot 2016-06-05 at 7.42.38 AM.png

          • 2. Re: Motion Tracking help
            armoose Level 1

            Hey Rick thanks for the help! You always give great suggestions...thanks! Ill give it a try and see what comes out of it. I'll let you know if any complications arise. Thanks again!

            • 3. Re: Motion Tracking help
              armoose Level 1

              So I tried to track it in mocha. I tried tracking the whole hand like outlining it in track points. What I got is this (view video below). Is there any advice on how to make it look less jittery. Is that just that I need to get a better track in mocha? What should I target since the hand is facing different directions throughout the shot? I did a track than copy pasted the tracking data into AE. I could try to corner pins idea from mocha but it didnt seem to work too well. Also is there a way to make the screen itself look fuller three dimensionally? I liked the exposure effect you did but I kinda want to keep the screen that was on the computer beforehand. Any advice would be greatly appreciated. Thanks again.


              The link to the video is below

              ScreenReplacementROTO - YouTube