How does Motion Path easing work?

I'm hoping someone can help me figure out how the logic behind the motion path duration, easing direction and speed settings work together. 

I have 4 identical images set up on a slide. The images are aligned left and each has a straight line motion path of the same length.

The duration is the same for each (5.25 s)

Option 1:

When I apply Ease In to the images and assign a different speed to each one (slow, medium, fast, very fast) this is what I see:

  • The slow image starts first. 
  • The very fast image starts last.
  • All images finish at the same time.  

In this case, I expected to see the opposite result in that the image with the slow speed would ease in slowly and the one set to very fast would ease in the fastest.  I also expected that all 4 would finish in 5.25 seconds which is the duration set for each motion path.

Option 2:

When I apply Ease In/Out this is what I see:

  • Slow starts first but finishes last.
  • Very fast starts last but finishes first.

In this case, I expected that the slowest image would ease in slowly and ease out slowly and very fast would ease in quickly and ease out quickly. I also expected that all 4 would finish in 5.25 seconds which clearly is not the case because they all finished at slightly different times.

Option 3:

When I apply Ease Out this is what I see:

Slow starts last and finishes last.

Very fast starts first and finishes first.

In this case, I expected each image to start and finish at the same time, but the ease out would be faster or slower depending on the speed setting.


5 Replies
Alyssa Gomez

Hey Nancy!

High school Physics class is coming back to haunt me. 😁 Motion path logic is based on 3 variables: speed, distance, and time. 

Since all objects are moving the same distance, that means objects moving at a faster speed are going to reach the end of the motion path in a faster time.

If a fast moving object and a slow moving object traveled the same amount of time (5.25 seconds), then the fast moving object would end up traveling farther, which we don't want.

In case you're a visual learner like me, check out my explanation in this quick Peek video. I hope that helps to clear up any confusion, and let me know if you have any more questions about that!

Nancy Woinoski

Thanks for the peek Alyssa. I understand what you are saying but I guess my mind works in a different (maybe not entirely logical) way.

My understanding of an ease in & out animation, for example, is that it starts out slowly and gradually gets  up to top speed where it remains steady until it  gradually slows down at the end. Kind of like a car accelerating to merge into traffic and then driving along until it has to slow down to come to a stop.

It is also my understanding that the speed settings control the rate at which the acceleration and deceleration occur (the speed settings are grouped under easing in the menu) - not the overall duration of the trip.  

If my assumptions are correct then it is my view that the overall duration of the the animation should not change based on how fast the car accelerates or decelerates at the start and end of the journey. Storyline should instead adjust the speed at which the object travels to ensure that the animation stops at the set duration. In other words, the duration should take precedence over how fast the object travels.

I also agree with Michael about the speed settings. It would be great if we could set it in relation to the overall duration and it would be great if we could set different ease speeds at the start and end points.