How to map blur to position for film-jitter like effect

Forum|Forum|1 year ago
December 19, 2024
2 replies
1373 views

I am using the "wiggle" expression on Position to create a film jitter effect.

How can I map a blur to the position of the layer, so that it blurs in relation to the movement caused by that jitter? I'm not looking to blur the images in the footage based on their 'motion' (ie - the baseball flies across the screen - I'm not looking to blue that) but just a motion blur based on the movement of the whole frame.

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Correct answer Dan Ebberts

You could try applying a Directional Blur effect to your footage and tie the blur Direction parameter to your Position wiggle's velocity with an expression like this:

v = position.velocity;
-radiansToDegrees(Math.atan2(v[0],v[1]))

and use an expression like this for Blur Length:

m = .5;
position.speed*m

where you adjust the multiplier variable (m) to get the amount of blur you want. Something like that.

Dan Ebberts

Correct answer

Community Expert

You could try applying a Directional Blur effect to your footage and tie the blur Direction parameter to your Position wiggle's velocity with an expression like this:

v = position.velocity;
-radiansToDegrees(Math.atan2(v[0],v[1]))

and use an expression like this for Blur Length:

m = .5;
position.speed*m

where you adjust the multiplier variable (m) to get the amount of blur you want. Something like that.

P

paul_7484Author

Known Participant

Thank you. I guess this is more invovled than I thought.

Where do those expressions go exactly? The expression starting with v = goes in the Wiggle expression and the one with m = in the Directional blur? What is the syntax exactly? And then tie wiggle Position to Directional blur Direction with the pick wick?

Dan Ebberts

Community Expert

Great, I will be reading up on how to use the expression syntax.

You'll find info on velocity, speed and radiansToDegrees() in the Expression Language Reference of AE's Help, and Math.atan2() in any JavaScript reference.

Mylenium

Legend

Could be as trivial as feeding the wiggle() as a driver into a linear() expression to remap the value ranges. The only prerequisite would be for the wiggle() to exist on a "neutral" control before feeding it into anything or else you end up getting weird values and inconsistencies in the randomness. So apply the wiggle() to a custom expressions slider and then feed it into the position and blur with a pickwhip expression.

Mylenium

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