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tracking speed to control frame rate

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Daniel Cantwell
tracking speed to control frame rate
on Apr 25, 2019 at 2:59:45 pm

Howdy Folks

I was wondering does anybody have any experience controlling frame rate with the speed curve of tracking data. I am sure it should be possible to have a linear camera move rendered out at a high frame rate (provided the distance rendered is the same as a live action camera) and have the speed of a live action track control the frame rate to get the appropriate ease in and out. Any help with this would be greatly appreciated.


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Filip Vandueren
Re: tracking speed to control frame rate
on May 1, 2019 at 2:44:02 pm

It depends… if you're tracking 2D data, the position of your track would indeed have a linear relationship to distance traveled. You can integrate and scale that by a value that is dependant on the actual amount of mpixels travelled. Easiest would be to tweak that value with a slider.
Something like the attached expression would work (in theory !).
Maybe checking the speed at every frame-duration wouldn't be accurate enough, just change the fd = line and adjust scalingFactor accordingly…

scalingFactor = effect("Slider Control")("Slider").value;
trackingProp = thisComp.layer("2").transform.position;
fd = thisComp.frameDuration;
delta = 0;
for (t=0; t<time; t+=fd) {
delta += trackingProp.speedAtTime(t);
}
d=(delta/scalingFactor);

valueAtTime(d);




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