• Adobe After Effects Expressions

  Random Scale/Rotation/Level values.

  Posted by Rick Symonds on November 27, 2009 at 10:49 pm

  Hi there,

  I’m pretty new with AE, especially when it comes to expressions. I’m trying to figure out a way to add random scale and rotation values to multiple layers in after effects. I’m working on a music video that involves creating a photo mosaic look.

  https://www.enseignement.polytechnique.fr/profs/informatique/Francois.Sillion/Majeure/Projets/teyssier/Images/hockney.furstenberg-paris.jpg

  I’m trying to work out a manageable workflow that will enable me to achieve this desired look. I am thinking about using an action in Photoshop to “cut” my image into sections then animate them in after effects. I basically want each square/layer to animate on with a slightly different scale/rotation/exposure level to sell the homemade collage look.

  I’m obviously working with a really large number of layers and I want to be able to do this as easily as possible. I don’t want the values to change over time. I simply want each layer to pop up with slightly different scale,rotation, levels value.

  I hope that makes sense. If anyone could point me in the right direction I would be really grateful and if you need anymore information/explanation just ask.

  Thanks!

  Rick Symonds replied 16 years, 9 months ago 2 Members · 4 Replies
• 4 Replies

• 

  Dan Ebberts

  November 28, 2009 at 12:11 am

  I’m not sure what you have in mind for the “animating on” part, but you’ll probably end up with something like this for scale:

  minVal = 75;
  maxVal = 125;
  seedRandom(index,true);
  s = random(minVal,maxVal);
  [s,s]

  and this for rotation:

  minVal = -15;
  maxVal = 15;
  seedRandom(index,true);
  random(minVal,maxVal)

  One you have an expression set up for one layer, you can select that property, Edit > Copy Expression Only, select all your other layers, Edit > Paste.

  Hope that helps.

  Dan
• 

  Rick Symonds

  November 28, 2009 at 1:49 am

  Thanks for the fast response Dan!

  Do you have a suggestion as how I could go about creating a random exposure level for each photo? Would it be a similar expression added to a levels effect?

  Thanks so much for your time. You’ve been a really big help.

  Rick
• 

  Dan Ebberts

  November 28, 2009 at 3:08 am

  Sure, or you could try the rotation expression on the Brightness and Contrast effect and mess around with minVal and maxVal until you get something you like.

  Dan
• 

  Rick Symonds

  December 2, 2009 at 2:48 am

  Thanks!!

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