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Activity Forums Adobe After Effects Expressions is it possible to us expression for exponential scale?

• # is it possible to us expression for exponential scale?

Posted by on April 27, 2005 at 3:21 pm

hello Dan and everybody, i just wondered if it is possible to use expression to achieve the same result as using exponential scale, so, i can modify the from/to value more easily? say, from 25% scale up to 2500% in 5sec, how to write the expression for this interpolation? thanks

ryan

4 Members · 4 Replies
• 4 Replies
• ### Dan Ebberts

April 27, 2005 at 3:46 pm

Try this:

``````
v1 = 25;
v2 = 2500;
t1 = 0; //start time
t2 = 5; //end time

if (time <= t1){
s = v1;
}else if (time > t1 && time < t2){
t = time - t1;
T = t2 - t1;
k = Math.log(v2/v1)/T;
s = v1*Math.exp(k*t)
}else{
s = v2;
}
[s,s]

``````

Dan

• ### Andrew Kramer

April 27, 2005 at 3:58 pm

Dan this is very creative how you solved this. Do you think you can explain it a little bit. Also could this be done with a linked slider.

so if you keyframed the expression slider value at say 10 and then to 100 equal to scale would be 100-10000.

this way you could alter it visually with keyframes.

thanks
Andrew

• ### Ryan Chan

April 28, 2005 at 1:53 am

thanks Dan, you,re incredible! although it is far more complicated than i expected, but i will try to “Digest” this expression, thanks again.
ryan

• ### Mike Clasby

April 28, 2005 at 8:01 pm

Very cool little expression. It looks great on a 3D solid in Custom view 1, so you can actually see what’s going n. Thanks.

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