Extract a curve from a movement

like that?

nice opportunity to give the new behaviour ALIGN TO a shot…

my set is like this:

'system' is your set, the blue dot, orbiting on the yellow circle around the blue one ....

Now, I made me a tiny green dot, hit E as in ParticlE, and applied to the Group an ALIGN TO behaviour - the new kid in town, under Behaviours/Basic, in vers 5.3 - to the (moving) centre of the blue dot.

set the Cell controls 'Speed' to zero, but the Birth Rate to 100, or 200 (depends on how fast the Blue Dot is orbiting).

Thats all: the Emitter spits out hundreds of dots which form a line, and the Emitter 'attached' to the Bluey creates a nice curve ..

cool? 😉

What I like most:

even on my low powered MacMini I can adjust the rotation speeds (rates) 'interactively', aka 'live' ...

Here's old school, very simple, just to throw it out there.

A is the big circle.

B is the smaller circle orbiting A.

C is the smallest circle orbiting B.

Draw B and C.

Place a Motion Path Behavior (Basic Behavior group) on C.

Change its "Path Shape" to Geometry and drag B into the source well.

Now, this is important; make a new Group, OUTSIDE of the Group that B and C are in.

Inside this new Group, draw A.

Place a "Motion Path" behavior on the Group containing B and C. Not on B or C, but on the GROUP that contains them.

Change its "Path Shape" to Geometry and drag A into the source well.

You can adjust speeds with the number of Loops set for each Motion Path behavior.

Or apply a Link behavior to one of the Loop parameter, link it to the other, control both with one control.

Then apply the emitter that Karsten mentions.

Not sure you can do that. Motion isn't great at gathering and giving that type of data. Kirsten's method of using an emitter isn't drawing a line of any sort, just leaving a bread crumb trail of dots, which appear to us as a line. No real data there.

Unless you wanted to use the B-Spline tool to draw over what the emitter is creating?

What exactly is your final goal? Perhaps there is another way to achieve it? What exactly are you trying to do with this newly created path data?

Alex470 wrote:

… extract this movement as a bezier or a B-Spline curve ?

uhm, well not with Motion alone.

What you can do:

that 'breadcrumbs' are on their own layer.

export that as jpg or png

use any VECTORIZING tool, there are several free services on the net, and several apps avail, to convert a pixel graphic into a bezier/Illustrator file/format …

… Kirsten …

<cough> just because Mrs Dunst is a little bit more popular than me, autocorrect makes me a woman ..... 😟

Alex470 wrote:

My goal was to use this bezier curve as a dashed line

… then vary the Birth Rate in the Emitter:

Alex470 wrote:

With dash like that 🙂

… then use a tiny line instead of a dot/circle as emitter …

When your next question is, in a different color, I get grumpy … 😝