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Expressive Camera Dolly?
Is there a way to write an expression to move a camera in 3D space at a constant speed independent of shot length?. In other words, I have hundreds id shots to composite, they all need to be a camera dollying right or left. All the cameras need to be moving at the same speed. All shots are different lengths. Is there a way to write an expression that would take into consideration the track’s length or the amount of frames in between two keyframes and determine it’s speed. This speed is what needs to be a constant in all shots. The distance that the camera moves will obviously be different from shot to shot. It would be great if a shot is very long, that the camera stops for a second at a keframe and then start to move in the opposite direction. Too confusing?. I’d like to mimis a camera on a dolly moving side to side at a constant speed, irrelevant of shot length. Possible?.
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2 Replies
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this will give you constant movement on the x axis of a 3d camera:
rate = 1;
x = Math.abs(position[0] * time) * rate;
value + [x,0,0]a positive rate value, will give you left to right movement, negative right to left… the initial x position is just the x position of the camera, this could be a set value like 500, if you needed. just change the ‘position[0]’ to the value needed.
if i have a little more time, i’ll look into the keyframe direction change, or would it be better to have a set time, like 10 seconds, and then the camera chagnes direction… i also assume you would want it to ease in and out of the direction change?
Kevin Camp
Designer – KCPQ, KMYQ & KRCW -
Don’t really know what you want. “All the cameras need to be moving at the same speed. ” There is only one Active camera in AE, the top one with it’s eyeball on.
Here are the only two automated camera setups I know of.
1) Dan’s, Building the World’s Greatest Cameraman, the last comp “—pan, tilt, focus, and zoom—“, here:
https://library.creativecow.net/articles/ebberts_dan/expression_cont.php
It uses keyframes on a Slider (under the Null) to tell the camera which layer to focus on next.
There’s a lot going on there, but if you turn off all the expression on the layers larry, james, evol and dan, then line them up in the order you want them seen top to bottom, then change the keyframes to 1,2,3 and 4 in the Slider in the Null, along with moldyboot’s expression on camera Positing (to give you the constant speed, you get (maybe ) what you want. If you arranged the keyframes to match the shot lengths (inpoints and outpoints) you might just have exactly what you want, but that final, tying the shot length to keyframes placement with expressions is way beyond my paygrade, if it’s even possible.
Methinks you’re asking for a miracle.
2) And this script:
autoOrientCamera
https://www.nabscripts.com/Downloads/downloads_en_1.php?id=1
The camera speed is not constant, it changes focus depending on where you place markers in the top layer, before you run the script, it then creates a camera with keyframes.
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