Motion Sketch convert to rotation value?

[Steve Roberts]

Hmm … off the top of my head, if you could make a null follow (pickwhip position expression) the motion sketch, then pickwhip that position to the point of interest of the camera … but then you’d have to … oh, I’m tired. Anyway, if the point of interest moves around, the camera will swing to follow it. How it turns into a banking motion, hopefully you can fill in for me.

Anybody else?

[Reynolds Strother]

Figured it out. Just in case someone looks into this post I wanted to tell my findings.

By the way you don’t even need a custom expression to do this… And to clear things up I was looking for a way to independently control a slight wobble or side to side tilting of the camera. This is essentially “wiggling” the camera’s Z_rotation by using motion sketch to have some nice organic control of the rotation. (remember that motion sketch can only be applied to a position value, so the trick is to use it to change a rotation value)

Here are the steps:

Create a Null (name it “camera_Z_bank” or “camera_Z_rotation”, whatever the heck you like).

Leave it as a 2d layer. (you only need the x_position value, a 3d layer still works, just not necessary).

Go back to the camera, twirl down the z_rotation stopwatch to create an expression.(alt + rightclick the stopwatch)

Use the expression pickwhip to link the z_rotation of the camera with the position value of the Null you just created. That’s all you need to get the expression.

Now the camera will rotate on its Z axis when you change the X value of the Null’s position.

Apply motion sketch to animate the Null’s position allowing you to give “awesomely, randomized, organic” movement to a rotation value for the camera.

I’m new to using any expressions even in the simplest ways. There could be another way to achieve this but, this is still pretty simple and easy.

[Reynolds Strother]

Need to clear two things up, sorry.

1. The Null does need to be 2D, motion sketch requires it.

2. It is a good idea to take the default expression you get form the pickwhip and divide the value by a large number (10-100).

Looks like this to start with.
thisComp.layer(“camera_z_bank”).transform.position[0]

Now just add the division to the end. I used 90.
thisComp.layer(“camera_z_bank”).transform.position[0]/90

If you don’t do this the rotation will be very dynamic/sensitive to motion sketching. This allows smoother movements.

[Tim Osborn]

This was helpful to me – thanks, I didn’t think of using the Null..

For posterity, my variation on this technique is to:

• create a null
• create a motion sketch path on the Null layer
• right click the null.position property and ‘separate x&y’
• select the keyframes from x or y
• click on the destination layer’s rotation value
• Move the playhead to the desired time and paste!

Note that to edit the keyframe values, you can select a range of keyframes, click on their value field and type *-0.5 (for instance), to modify them all mathematically..

Not a complete solution – I actually found the result impractical because the values spun too wildly for my needs.. just thought I’d share, as I appreciated the OP’s tip!

Cheers, Tim