• Adobe After Effects

  Motion tracking for video through car windows

  Posted by Phil Beastall on April 21, 2008 at 9:18 am

  I have some greenscreen footage, tracking up to the front of the interior of a car. so it starts near the back and moves forward around a metre on a track forward. Can anyone tell me the best way to track this motion to then apply to some video footage to put through the windsceen and side windows? I have tracked the movement of two headrests but the background wouldn’t simply work like that, because as you get closer to the windscreen, you would start to see more footage through it?

  Any ideas?

  Jeremy Allen replied 18 years ago 4 Members · 3 Replies
• 3 Replies

• 

  Steve Roberts

  April 21, 2008 at 12:27 pm

  So they didn’t add markers to the background? Tsk.

  If it’s just a track forward, you might be okay if the footage only has distant elements in it, since on such a short track, you shouldn’t notice a perspective change in distant elements. Maybe a slight scaling up of the background footage as you track in …?

  Anybody else?
• 

  Brian Berneker

  April 21, 2008 at 4:25 pm

  I’m thinking adjust your motion track for position and rotation but NOT scale. Or, scale it only a tiny bit, by applying the tracking data to a null and parenting your BG to the null with only slight scaling.

  Farther objects in the distance (i.e. mountains) tend to remain roughly the same size (not accounting for perspective objects, trees, the road etc.) I guess if your footage was shot out the back window of a vehicle it might be ok as-is, so I’m assuming you’re constructing the read window shot?

  If so, build it with 3D layers – I’ve found that 2D never pulls it off, especially with the side window stuff. You need parallax to make it work. I built an entire desert complete with joshua trees in trapcode Particular once just so I could have side window scrolling, and even then it was merely passable.

  Andrew Kramer has a tutorial on this very task in his Serious FX and Compositing DVD.

  https://store.creativecow.net/p/52/serious_effects__compositing

  Brian
• 

  Jeremy Allen

  April 21, 2008 at 7:56 pm

  This may help as well> I seem to remember him tracking a slight push-in on this project, but i could be wrong.. I didn’t have time to watch the whole thing again…

  https://www.videocopilot.net/tutorials.html?id=86

  Hope it helps..

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