7 Replies Latest reply on Oct 27, 2009 10:33 PM by Adolfo Rozenfeld

    Stabilizing - can I nest trackers?

    ingvarai Level 1

      I have a clip shot sideways from a moving car, country side, forest in the horizon. One layer up, I have a car, shot against a green-screen. I want to stabilize the landscape. I have tried Pro Dad Mercalli, SynthEyes and Mocha - can't get it stabilized.

      The problem is that all parts of the image soon will be replaced by new scenery, as the car moves fast (it is shot sideways). What I have done, successfully, is to use two trackers in After Effects itself. And I was able to get great results, both shake and rotation was solved.

       

      Now - this is for a few seconds, until the track points have moved off-screen. I am wondering, is there a way to add two new tracking points where the previous pair go off-screen, and continue with this until the scene is all covered? I would call this "nesting trackers". In short: Have a new set of trackers take over where the previous set stops.

        • 1. Re: Stabilizing - can I nest trackers?
          Adolfo Rozenfeld Adobe Employee
          Now - this is for a few seconds, until the track points have moved off-screen. I am wondering, is there a way to add two new tracking points where the previous pair go off-screen, and continue with this until the scene is all covered? I would call this "nesting trackers". In short: Have a new set of trackers take over where the previous set stops.

           

          Absolutely.

          But you don't need a new set of tracking points.

          If you alt-drag a whole tracking group (you have to point inside the group so the "move" icon appears), you'll see that you can offset the feature and search region so they transparently keep tracking a new feature in the source image, without producing any visible "jump" in the track. I think this is one of the most valuable tricks regarding the AE tracker.

          Is this clear? Let me know.

          • 2. Re: Stabilizing - can I nest trackers?
            Mylenium Most Valuable Participant

            Failing the offset adjustments, you can always bake existing data to a Null, then parent the layer to it and start a new track. Using scripts like KeyTweak it is quite easily possible to get those two things interpolated/ balanced to look continuous.

             

            Mylenium

            1 person found this helpful
            • 3. Re: Stabilizing - can I nest trackers?
              ingvarai Level 1

              Adolfo:

              > Is this clear? Let me know.

               

              Crystal Clear! Thanks a lot!! I was not aware of this at all. It works like magic.

              However, and this is not AE's fault, my footage is partly full of motion blur, as nearby trees pass by in front of the more remote horizon. I have come to the conclusion that, althoug your solution works great in other cases, that I will have to use Mocha. Mocha does not stumble when a tree comes along in the front, I just use a large track layer.

               

              The challenge with Mocha is to export several layers in one operation. I do not know how to do this so far. Everyone stabilizing and tracking seem to work with footages where the same image details are visible throughout the scene. The challenge arises when the whole scenery slides off-screen totally, and is replaced by new scenery, as the car moves along the road. I am looking for a solution where I can use Mocha, and export all Mocha layers in one operation. Otherways the process will be way to cumbersome. Any Mocha users, please chime in :-)

              • 4. Re: Stabilizing - can I nest trackers?
                Lost In My Mind
                If you alt-drag a whole tracking group

                Sorry Adolfo, messed with it for hours hoping not to ask a dumb question, but here it goes......I have CS4 and when I hover over the tracking group the pointer turns to the move tool, but whether I hold Alt or not, I can only move a single track point??????? I usually use Mylenium's method with the Null Object, but I'm always looking for better and different ways to do things. Thanks.

                • 5. Re: Stabilizing - can I nest trackers?
                  Adolfo Rozenfeld Adobe Employee

                  Lost in my mind:

                   

                  I assume what you meant when you said that you could only move a single tracking point is that in the case of tracking rotation, scale, etc(ie, cases where two or more features have to be tracked) the second tracking group doesn't move at the same time when you alt-drag the first one?

                   

                  What alt-dragging allows is to pick a different visual feature (typically when the feature you were tracking goes off screen, or is obscured by something else) in such a way that there isn't a jump in the resulting  position, scale or rotation. So, if you have two tracking groups (by group I mean the feature/search rectangles), you can alt-drag both tracking groups to pick different features from that point on time forwards or backwards. If you just drag instead of alt-dragging, the resulting tracking data will show a violent jump at the point in time where you moved the feature region.

                   

                  If you just mean that the search rectangle (the outer one) moves separately from the feature region or vice-versa, it's just a matter of pointing at the area between the two rectangles, instead of the rectangles themselves.

                   

                  I hope this is clear now.

                  • 6. Re: Stabilizing - can I nest trackers?
                    Lost In My Mind Level 1

                    Thank you Adolfo for having the patience and taking the time to clarify that for me. I get it now, and yes that is a great feature. I have to remind myself that 'there is no such thing as a stupid question, only stupid people asking questions.'    Cin

                    • 7. Re: Stabilizing - can I nest trackers?
                      Adolfo Rozenfeld Adobe Employee

                      I am glad it's clear now.

                      Just to make it even more clear:

                      Normal dragging (no alt) the feature/search combo is something you typically do in the first frame in which the tracker fails to stick on a feature. In that case, you're actually animating a correction in the tracker stream, and in most cases, the tracker will keep tracking accurately from that point on.

                      Alt-dragging means that there's no animation. Just stick on a new feature you pick, and use this new feature to continue transparently from that point on. If instead of stabilizing, you're tracking motion, the attach point (ie, the target point for the track) will be transparently offset from the feature/search rectangle combo.