3 Replies Latest reply on May 19, 2014 5:30 PM by Rick Gerard

    How do you track 4 coner pins of a composition 4 corner pins


      How do you track 4 coner pins of a composition 4 corner pins


      Hi guys.



      Can you watch my screencast and help me with it?




      I tried to search everywhere but I couldn’t find answers, maybe wrong keywords.



      Is there a way to track the 4 cornorpins of the composition?





      I am doing some project related to 4 cornorpin.



      http://blog.dotify.fr/nteractive-video-with-4-corner-pin-motion-tracking-after-effect-flas h/

      like this..



      I know I could do a black solid layer in to “footage holder 6 pre-comp” and track with 4 corner pin.



      But I wanted to know if there is a way to track the pins w/o rendering.



      As it should be the most precise way to find conor pins







      Can you help?




        • 1. Re: How do you track 4 coner pins of a composition 4 corner pins
          Dave LaRonde Level 6

          There is no need to track anything.  These are 3D layers whose rotation is controlled by a null object.  You can save the temp;late under a different name, and use the Replace Footage command to put your own precompositions where template's precomps are in the timeline.  It's very simple.

          • 2. Re: How do you track 4 coner pins of a composition 4 corner pins
            PrayerHwang Level 1

            Thanks for reply.



            Just like the project in

            http://blog.dotify.fr/nteractive-video-with-4-corner-pin-motion-tracking-after-effect-flas h/ .




            I want to make a script that can show replacing placeholders in the footage.




            To do so, I need coordinates of 4 corner pin of a composition(the composition which I can replace the footage).




            Of course, I can put a placeholder with dots, render the project and then motion track it.

            But it takes long time and tracked data is rusty and inaccurate.




            I thought it mightbe cool if I could just keep tracking the vertax's x coordinate and y cordinate data.

            It will be precise, clean and quick since the positions of the dots are already calculated.


            Can you help?

            • 3. Re: How do you track 4 coner pins of a composition 4 corner pins
              Rick Gerard Adobe Community Professional & MVP

              The comp you showed us in your first post contained a 3D layer. If you want to corner pin track that layer then you have to pre-compose the layer and use corner pin tracking. The comp isn't really that good of a candidate for corner pin tracking because of the extreme perspective changes. The key to good tracking is a target that is about 100 pixels minimum and has some detail. Just putting small dots in the corner of the layer you want to track isn't going to cut it. You need details to get a good track.


              If your project requires corner pin tracking data then Mocha's planer tracker or AE's corner pin tracker is a good and accurate option.


              The other option would be to attach a 3D null to each corner of your animated 3D layer, make the nulls the children of the 3D layer (parenting) then write an expression that would take the toComp values from each of the nulls and then use the Keyframe Assistant to convert the corner expressions to keyframes. I wouldn't try to write that expression off the top of my head but it is pretty straight forward if you do a little research.


              If you are trying to replicate the Facebook player app, then follow that tutorial series and you'll have to use the apps the author used to make things work.


              If you are trying to make an After Effects template then you don't have to do anything but pre-compose your 3D layer, then instruct the user to replace the footage in the pre-comp with their own footage.