• Adobe After Effects

  Camera in After Effects

  Posted by Rory Flynn on August 25, 2010 at 10:00 am

  Hi,

  Is it possible to measure the distance from the camera to the object in after effects?

  I am working on a project with a client where I have to match an after effects camera move to real footage. Usually I would have done this the other way round. I would film it first then track the footage in after effects and create the scene that way. But my client wants me to make the scene in after effects first and then they will shoot the footage accordingly. Therefore they have asked me to let them know the lens size and distance from camera to object in each shot.

  Does anyone know how to do this?

  Thanks

  Rory

  Rory Flynn replied 15 years, 11 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Bartek Skorupa

  August 25, 2010 at 11:23 am

  This shouldn’t be any problem.
  When you add a camera – you chose the preset, for example 50mm. This is the focal length. You give this info to the client and that’s it.
  I assume, that you will not change the zoom value over time. If you do – it’s a little bit tricky, but also possible to calculate.

  And now the distances:

  You can easily measure the distances between the objects with a simple expression.
  Add any layer and give it a “slider control” Add an expression:

  length(p1,p2)

  p1 and p2 are the positions of the layers. The expression will return the distance between them.
  p1 and p2 can be easily pick-whipped. The result will be the distance in pixels.

  Then you have to say how many meters, millimeters, feet or whatever this is.
  And this is up to you. You have to simply ask yourself what is the size of your world.
  You have to specify how much pixels represent some real world unit, like meter or foot.

  It is good to work with square pixels in such cases.

  Bartek Skorupa
  Warszawa, Poland
• 

  Rory Flynn

  August 25, 2010 at 8:01 pm

  Hi,

  Thank you both for your replies. much appreciated. That is what I was thinking Dave. Will have to try and persuade them to do it the other way round. Shoot first and then track it. Oh well, thanks anyway.

  Rory

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