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David228309536y3q
Participating Frequently
April 11, 2022
Answered

I have motion tracked an object in a clip & I want the frames to follow the object, how do I do it?

  • April 11, 2022
  • 3 replies
  • 693 views

So I have used motion tracker and tracked an object moving in a clip, I know how to edit target and apply it to a null object and then pick whip things such as text and other layers to that null to apply the tracking data to them so the image/text/etc. will follow the object I have tracked. However, I don't know how to apply the tracking data to the footage itself so that the actual image will follow the object I'm tracking. So the tracking data is essentially plotting what the centre of each frame will be focused on.

 

I know how to do this with a camera layer but I was wondering if you can do without one. I hope I've explained what I'm trying to do clearly. Sorry if not

This topic has been closed for replies.
Correct answer Mylenium

That guy doesn't know what he's doing and just clowning around! Here's some better ones:

 

https://www.youtube.com/watch?v=brHGchYW_NU

 

https://www.youtube.com/watch?v=q2lzMKkq_cg

 

Mylenium

3 replies

Mylenium
Mylenium
Legend
April 13, 2022

As per my initial reply, you can just copy & paste over the keyframes, then invert the values by subtracting them from the layer's default position/ size like:

 

X=thisLayer.width*0.5-value[0];

Y=thisLayer.height*0.5-value[1];

 

[X,Y]

 

There's also several useful tracker scripts on AEScripts.com which can help to boost your workflow:

 

https://aescripts.com/after-effects/tracking/

 

Most of them cost at least a few bucks, though, but if you do this often, they're easily worth their money.

 

Mylenium

    D
    David228309536y3qAuthor
    Participating Frequently
    April 13, 2022

    thank you very much for this. I'll keep this post pinned. Oh and on this specific occasion I didn't actually apply my motion tracking to a null or an object yet so I simply had to switch the tracking type from transform to stabilise so I didn't have to copy anything over thankfully but again I'll keep this pinned for future referece. Thank you very much for this mate, this is exactly what I was searching endlessly for.

    Mylenium
    MyleniumCorrect answer
    Legend
    April 11, 2022

    That guy doesn't know what he's doing and just clowning around! Here's some better ones:

     

    https://www.youtube.com/watch?v=brHGchYW_NU

     

    https://www.youtube.com/watch?v=q2lzMKkq_cg

     

    Mylenium

    D
    David228309536y3qAuthor
    Participating Frequently
    April 12, 2022

    ah I see, so I guess the technique I'm after is 'stablising' I guess, that's great thank you 🙂

    on a side note though, I've already got the tracking data in a tracker for motion tracking rather than a tracker for stablising. Is there anyway I can copy the data from my motion tracker to the tracker for stabilising? or do I have to re-track it all again

    Mylenium
    Mylenium
    Legend
    April 11, 2022

    That's what the stabilization options in the classic 2D tracker would do. After the fact you could copy & paste the data e.g. from your Null and write an expression that inverts the data. Entirely depends on what exactly is needed. a screenshot might help to clarify.

     

    Mylenium

    D
    David228309536y3qAuthor
    Participating Frequently
    April 11, 2022

    Oh it's pretty simple, I'm editing a clip for a streamer I know, and there's a person/character moving around in the clip. They want that specific character to be focused on while they move around, so basically they want the character to be tracked. So I've just motion tracked them (manually for the most part) and I want that tracking data to be used to set of key frames for footage's positioning so the camera/perspective of the clip follows the character. I normally apply the tracker to null object, then pick whip a 3D camera and then I just crop the image. I just wondering if I actually need a 3D camera layer to do this, from what I've heard I actually don't have to do that, I'm just making it more difficult for myself.

     

    (this is the turtorial I learnt the 3D camera thing from but he uses it to have the tracking track rotation as well as as movement and I don't need to track rotation so I'm not sure if me using a 3D camera is neccesary or if this is a bad habit Dynamic Camera to FACE MOTION TRACKING Technique In 5 Minutes Explained! After Effects 2020 Tutorial - YouTube)

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