8 Replies Latest reply on Apr 16, 2011 3:51 AM by Rick Gerard

# Can I make a speed displacement map?

Is it possible for me to for example play the very left of my clip at 10% of the original clip's speed and the right at 200% with a smooth gradient of speed change inbetween (10% ~~~~ 200%)?

I do not want to do the time displacement effect - which just plays back at normal speed. I want to displace the speed

Any help?

Many thanks

L

• ###### 2. Re: Can I make a speed displacement map?

No, I'm afraid that isn't what I am after. Please have a look at the picture below to help explain:

• ###### 3. Re: Can I make a speed displacement map?

The confusion may be in my phrasing. By 'left' I meant the left hand side of the image/frame/composition NOT the left side of my timeline (start)

• ###### 4. Re: Can I make a speed displacement map?

What you'll want to do is to animate the gradient you're using for the time displacement map. Time displacement sets the time of the current frame based on the luminance level of the displacement layer. If the luminance value is 50% gray there is no change in time. IOW the video runs at real time. If the CTI is at 2 seconds, the video is at 2 seconds.

If you were to set the displacement to 10, then a black value would move the time over black back 10 seconds and the time value over white forward 10 seconds. This means that if the CTI (current time indicator) were at 10 seconds the part of the frame over black would be at the in point and the video over white would be at 20 seconds.

So working out your request and figuring you want this effect to last for 10 seconds, your clip would have to be 20 seconds long to be long enough to play at 200% speed for 10 seconds. Your time offset would be 20. You'd animate the right side of the gradient from 50% to 100% white over 10 seconds so that the video on that side of the screen would move forward in time from the in point to the 20 second mark in 10 seconds. The left side of the screen requires some deeper thinking. You want that side to only be at the 2 second mark after 20 seconds which is where it would be if the video were running at 10% speed. Animating the luminance value of that side would go the opposite direction. You'd go from 50% to 10% over 10 seconds. This means that the time of the left side of the screen would go from the in point to 2 seconds in 10 seconds.

I hope you followed that. My math was done in my head so it may not be completely accurate because luminance values may or may not be linear, but the theory is absolutely correct.

Note: You can set the luminance value quickly in the color picker by simply typing the percentage directly in the B or brightness value.

• ###### 5. Re: Can I make a speed displacement map?

I've only ever known the Time Displacement effect to work on time, not affect speed.

I'll have to try this but even if you could get the pixels at light gray to update at a faster than normal framerate and the dark gray pixels to update at a lower than normal framerate, how would you combine them? I'd be doing this directly with two, may three clips, running at different speeds, with soft edge wipes between them or a more elegant way of blending the three layers.

bogiesan

• ###### 6. Re: Can I make a speed displacement map?

Turns out my math was a bit off and it's a little problematic to coordinate the 50% gray to black transition in the time displacement map so that things work, but Here's a sample comp. The three clocks are running at the same speed and the map, which I kept visible, is animated. Hope this helps and is useful to someone.

(note) I inadvertently rendered the whole 20 seconds so you'll see the far left clock speed up to real time at the 10 second mark.

• ###### 7. Re: Can I make a speed displacement map?

Thanks. You have helped me acheive what I wanted to do!

• ###### 8. Re: Can I make a speed displacement map?

Glad I could help...