Fusion Tracker Expression Sharing

Hi guys!
Is there a way to share tracker data between two separated Fusion Compositions? I have a background clip and several motion graphics with no background. Couple of them need to be sticked to background images. My point is to make a Tracker1 on Background layer as separated Fusion Comp and share Tracker1.TrackedCenter1, Tracker1.TrackedCenter2, etc. to individual motion graphics fusion comps. Any advise?

Is there a way to share tracker data between two separated Fusion Compositions? I have a background clip and several motion graphics with no background. Couple of them need to be sticked to background images. My point is to make a Tracker1 on Background layer as separated Fusion Comp and share Tracker1.TrackedCenter1, Tracker1.TrackedCenter2, etc. to individual motion graphics fusion comps. Any advise?

There's no way to link one comp to another in this way. Fusion only has the concept of the current comp - no way to say "dynamically use X from comp Y".

However, it's very easy to copy nodes between comps. So you could do your tracking in comp 1, then copy the tracker and paste it to comps 2 and 3. That'd work just fine, assuming the tracking data is appropriate for those other comps.

It does mean that if you needed to re-track, you'd need to re copy it to all comps using it. But if you can get it right the first time, it could work OK.

As there's no way to link to one central comp, there's no point breaking out tracking to its own comp. On your first clip, track your background, and use that Tracker to finish the comp. Then copy the Tracker, go to the second clip, copy in the Tracker, then finish that clip. And so on for each clip.

You do have the Macro feature for making nodes available to future comps. Again, it's not dynamic - making a macro just makes a copy of those nodes, which aren't linked live in any way. But if for example you knew that you'd need the same tracking data in 20 future comps, it might make life easier to make a Macro out of the Tracker (and any other common nodes). Then you could quickly add that same macro to each future comp, straight out of your tool list like any other tool.

But if it's just two or three that'll use the same data, or if the only common node is the Tracker node without any other common aspects between separate comps, I think I'd just copy it manually each time.

Nodes copy as plain text, so it's very easy to copy them around. And if you save a copy of a node as a .setting file you can then deploy it instantly in any future comp just by dragging that .setting file from disk into Fusion.

It would be awesome, but then I copy tracking node to second comp it's drops all keyframes. It stays in place. Do you know why?

It would be awesome, but then I copy tracking node to second comp it's drops all keyframes. It stays in place. Do you know why?

Copying a Tracker will definitely copy its keyframes.

My guess as to what's happening is that the frame range of your new comp is very different to the original, such that you're not seeing the copied keyframes because they're outside the composition range.

This can happen easily in Resolve because when one places a composition directly on a clip on a timeline, the Fusion comp that's created uses the frame range of the portion of that clip that's on this timeline.

Example: you have a 1 hour media file. On a 30 FPS timeline, you edit in minutes 30 to 33 of this clip. Then you go into Fusion. This Fusion comp will start on frame 54,000 and end on frame 59,399, because that's the portion of the original media file that's on this timeline.

If you track some part of that clip and then copy the Tracker to a different comp on a different clip, it could be using a very different frame range even if it's a clip from the same source media file. Copying your Tracker will bring in its keyframes, but they won't be in the right range for this new clip.

To investigate this, copy in a Tracker and then open the the Splines pane. If this new comp already has other nodes, it will make life easier if you click the three dot menu in the top right and choose Show Only Selected Tool. Then select Tracker1 so it appears in the Spline Editor.

With that done, click the Zoom To Fit button in the top right of the Spline Editor pane. This will zoom around the range of keyframes in the Tracker node, and you can see what frames they're on.

This example shows that I've copied in a Tracker with keyframes on frames 0 to 999, but my current comp is on frames 290789 to 291347:


You can try and fix this by:
- In the Spline Editor, select all the keyframes for Tracker1 (You can use Control/Cmd-A as long as no other splines are visible.)
- In the bottom right, click where it says "Time" and choose "T. Offset" (Time Offset)
- Type in the correct number to adjust the first frame of your Tracker to the first frame of this comp, then hit enter. In my example above, I typed 290789 because my Tracker keyframes started at 0, and this comp started at 290789.
- All the keyframes get moved in time by that amount.

Now I see keyframes on every frame of this comp:


OR: Avoid the problem in the first place by not putting Fusion compositions directly on clips. Instead, make a Fusion Clip or Compound Clip from the clip in question, and then put your Fusion composition on that. That will ensure every composition starts from frame 0.

I'm pretty sure that must be the problem you're having, but if it's not report back with some screenshots showing the before and after comps, and what the Spline Editor shows.