10 Replies Latest reply on Jul 16, 2011 8:21 AM by chande a k

    Motion Tracking a Dolly Shot


      I'm having a little trouble figuring this out. Thought someone on here might have done something similar.


      The shot: A person walks down a sidewalk. The camera dollies parallel to them so it sees a wide of their profile. The person disappears and reappears in the shot as the camera dollies. 


      Is there a good way to pull off a poor man's motion tracking effect like this? Certain plug-ins to use to get it right?


      A somewhat similar effect occurs a few (brief) times in this video: http://vimeo.com/24569304


      Happy to clarify if that doesn't make sense. Thanks in advance!

        • 1. Re: Motion Tracking a Dolly Shot
          Todd_Kopriva Level 8

          I don't undersand what you're asking at all.


          What are you trying to track? How are you trying? What are you having problems with?


          Are you trying to stabilize motion? Are you trying to composite a new element into a scene using motion tracking data?

          • 2. Re: Motion Tracking a Dolly Shot
            dueled Level 1

            I'm trying to make a person disappear in a dolly shot, but I don't have an expensive motion controlled rig.  Does that make sense?  It's more of a production + after effects question.


            I'm most likely going to have to have a plate where the actor is not in the scene as well as the original footage with the actor.  That means I'm going to have to capture two separate dolly moves and then composite them on top of each other.  I'm wondering what the best way to do this might be.  Since I do not have a motion-controlled camera rig, both shots will be slightly different.  I've done this for shots that are both locked off, but this seems like it's a different ball game.


            In the video I linked to in my original post, this effect occurs at 0:36. http://vimeo.com/24569304

            • 3. Re: Motion Tracking a Dolly Shot
              Dave LaRonde Level 6

              Since I have an old computer at my desk, I can't see vimeo footage.  From your description of the shot, it sounds possible to put the talent on a treadmill in front of a chroma key background, key the talent in and adjust the talent layer's opacity as desired.

              1 person found this helpful
              • 4. Re: Motion Tracking a Dolly Shot
                dueled Level 1

                Yeah, that could be one way of doing it. Definitely going to consider that for sure. But if you get a chance to look at the video I linked, it doesn't appear that's the case. We see the actor's entire body, feet included. Unless she was on a green treadmill, I'm still a little stumped.

                • 5. Re: Motion Tracking a Dolly Shot
                  Dave LaRonde Level 6

                  What law says you can't paint a treadmill Chroma Key Green or Chroma Key Blue?  Matching the background shot to the chroma key shot wouldn't be a delight, nor would matching the speed of the treadmill and the speed of the dolly... plus keeping the speeds consistent.  That's why God invented Motion Control.


                  I still can't see vimeo.

                  • 6. Re: Motion Tracking a Dolly Shot
                    bogiesan Level 4

                    That video is not meant to be seamless. The edits are obvious. If you want to maintain some kind of elegance, you will need matched shots, true. But even a motion control rig cannot compensate for the fact that the sun is going to move, shadows will shift, clouds will come in or out, something in the scene will change. You can probably achieve most of the elegance you are seeking with a simple mask around your talent, I don't see a need for chromakeying. But, yes, absolutely, the two plates will need to be photographed at the same dolly speed and camera position. You will want to use a slate/sticks to help you sync the clips and, if at all possible, an audible click track, someone counting out loud or something like that.


                    You know, AE is only your compositing system on this project. You might find much better advice on the shooting techniques on other forums.



                    • 7. Re: Motion Tracking a Dolly Shot
                      chande a k Level 1

                      It appears that Video is edited in Adobe Premiere or any other Video Editing software., and to give effect of Lady being disappear some frames are grabbed and in Photoshop portion ( LADY ) is content filled  so that it appears that lady has been disappear... not a difficult task, can be done in few minites

                      • 8. Re: Motion Tracking a Dolly Shot
                        Rick Gerard Adobe Community Professional & MVP

                        Here's what I'd do. I'd shoot a clean take of the actor with a dolly shot with the dolly on track if possible and the camera locked off. Have an assistant keep track of the time.


                        Once you have a clean take, roll back and take another shot.


                        If you don't have a dolly and track then do the best you can to keep the shot as close as you can to the "good" take.


                        Now you need to track both shots in Mocha. There a re tutorials on how to track a moving shot available. You would stabilize both shots, lay the clean plate over the plate with the actor and crop it with a soft edge mask big enough to cover the actor. Did you get that? You want to lay the clean plate over just the area where the actor is. Make any adjustments necessary to the timing of the shot to keep things lined up by using time remap on the clean plate.


                        once you have the composited shots looking like there's no actor in the shot , then you can use transitions, fades, or other effects to bring in your actor by eliminating the top clean portion.


                        Once this is all set up, remove the stabilization on the actor plate making sure that the clean plate is tied to it by parenting.


                        Don't expect to be able to hold this hide the actor effect for more than a few seconds without dolly track. If you carefully watch the reference  video you'll see that there's not a lot of exact frame matching going on. There just kitschy transitions between takes. The first one is especially awkward and there's a big jump that's hidden fairly well by the transition. In fact, I can't see anything except the distortions of the sidewalk and the overlays that probably used motion tracking. 

                        • 9. Re: Motion Tracking a Dolly Shot
                          chande a k Level 1

                          Yes I understand what you are saying and refering to example Video.....   But to do the perfect good finish job.,  it can be done as suggested by me earlier..I am a Photographer/Videographer and am in this trade since last more than 40 years., on many a occassion we have done this without any mismatch...taking the same shot twice, you can't do the perfect match....this is my practicle experiance... Still I am not master in doing the things in After Effect... If you all think it can be achieved in the way you are suggesting... We don't take that type of risk.


                          We just put first shot with Actor in Adobe premiere time line, and grabbed the frame or frames where we want that effect of disappearange., take that frames in Photoshop remove the actor with contents fill and then finish it nicely it hardly takes minitus... then we replace these frame from where it were grabbed...   You will have very nice perfectly finished movie.. If I had to do this thing, I will do as suggested by me..., not otherwise...  Thank you for your opinion

                          • 10. Re: Motion Tracking a Dolly Shot
                            chande a k Level 1

                            Let me first confess that I had not seen the entire video when I replied first...  but took the essence that effect has to be created to make few frames without actor ( Disappearance in few frames ).... After seeing it carefully repeatedly.. I have formed the idea that this work has been done very crudely... no planning nothing.,   and there are more effect than only disappearance of actor., all the rest of the effect clearly indicates that same has been done in premiere / photoshop., whereever effect of disappearance of actor ( Lady ) is it is  only for 2/3 frames and not more..


                            Why I suggested for doing in Adobe Premiere is I am more familiar with Adobe Premiere / Photoshop., and have only working knowledge of Adobe After Effect... You all participants in the forum have better idea/experiance., what can be achieved and how it can be achieved in After effect