• Adobe After Effects Expressions

  Changing Parameters based on Distance from Camera?

  Posted by Todd on July 7, 2007 at 10:19 pm

  Thanks to the previous help on these forums I’ve got a ring of layers orbiting around a center null. Because they are parented, on orbit, their position doesn’t change.

  I’d like to create an expression that can modify lets say opacity and a fast blur based on each layers position from the camera. The camera is stationary and the farther away from the camera (fixed point is max distance) I would like the more transparent and more blurry.

  DOF works, although the blur isn’t as nice as a gaussian or fast blur would be so I’m thinking of using that instead and turning DOF off.

  Anyone have a starting point for me to mess around with?

  Darby Edelen replied 18 years, 10 months ago 3 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  July 7, 2007 at 10:41 pm

  Here’s an example for opacity. You’ll need to adjust the parameters to fit your situation:

  minDist = 600;
  maxDist = 800;
  minOpacity = 30;
  maxOpacity = 100;

  d = length(toWorld(anchorPoint),thisComp.activeCamera.position);
  linear(d,minDist,maxDist,maxOpacity,minOpacity)

  Dan
• 

  Darby Edelen

  July 9, 2007 at 5:35 pm

  [todd] “DOF works, although the blur isn’t as nice as a gaussian or fast blur would be”

  Or a Box Blur for that matter (;

  I’d stay away from Gaussian Blurs, they’re not that pretty and they take a lot more time to render.

  A Box Blur with iterations at 3 or 4 is almost exactly the same as a Fast Blur, but it gives you the ability to fine tune the blur for your needs (fewer iterations = faster render, more boxy blur, more iterations = longer render, less boxy blur)!

  Darby Edelen
  DVD Menu Artist
  Left Coast Digital
  Aptos, CA

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