Tracks¶

A track is an identity that persists across frames — "this is the same mouse as the one in the previous frame." Poses without tracks tell you what was there; tracks tell you who.

Assigning tracks¶

Action	How
Create a new track	`Cmd`+`0` / `Ctrl`+`0`, or Tracks ▸ New Track
Assign the selected instance to a track	Tracks ▸ Set Instance Track ▸ …, or right-click the instance's body ▸ Assign Track (once the project has tracks)
Assign the selected instance to track 1–9	`Cmd`+`1` … `Cmd`+`9` / `Ctrl`+`1` … `Ctrl`+`9`
Copy an instance's track	`Cmd`+`Shift`+`C` / `Ctrl`+`Shift`+`C`
Paste a track onto an instance	`Cmd`+`Shift`+`V` / `Ctrl`+`Shift`+`V`

Cmd+1 … Cmd+9 (Ctrl+1 … Ctrl+9) picks the track by its position in Tracks ▸ Set Instance Track, which lists each track with its shortcut. If that track doesn't exist yet, the app creates Track 1, Track 2, … up to that number first, so you can start tracking with no setup.

Copy/paste of tracks is the fast way to fix a run of frames: copy the correct identity once, then step forward pasting it onto the instance that should carry it.

Renaming and recoloring¶

In the Instances panel:

Double-click a track name to rename it inline. Enter saves, Esc cancels.
Click the color swatch next to it to pick that track's color — a palette preset or Custom — or Reset to auto.

Transposing¶

Cmd+T / Ctrl+T (Tracks ▸ Transpose Instance Tracks) swaps the track assignment of two instances. This is the correction for the most common tracking failure: two animals cross paths and the tracker swaps their identities.

On a frame with exactly two instances it swaps them directly. With three or more, it asks you to pick the two.

Propagating¶

Tracks ▸ Propagate Track Labels is a toggle. While it's on, changing an instance's track (or transposing two instances) also swaps the identities on every later frame — to the end of the video, or to the end of the frame range selected on the seekbar. You fix a swap once rather than per frame.

With it off, a change applies to the current frame only.

Common tracking mistakes¶

Automatic tracking makes two kinds of mistakes. Both get worse the longer they go unfixed, because each frame's identities follow from the frame before.

Swapped identities¶

Two animals trade tracks, usually where they cross or touch. From then on, each track follows the wrong animal.

Find them: color by track (see Seeing tracks) and watch for an animal changing color. Three ways to get to the right frames quickly:

Where animals come close. Tracks ▸ Seekbar Header ▸ Min Centroid Proximity plots the distance between the two nearest animals. Swaps happen at the dips.
Where something jumps. A swap looks like a sudden jump in position. In the Suggestions panel, generate Velocity suggestions on a stable node, such as the torso rather than a paw, then step through them with Space. A higher threshold gives fewer, more likely frames.
Where trails cross. Set View ▸ Trail Length to about 50 and step through the video in big jumps (Cmd+Right / Ctrl+Right moves 10 frames). Trails that cross or tangle mark a swap.

With few animals, the five+ palette (View ▸ Color Palette) makes later tracks stand out; with many, alphabet gives each a distinct color. View ▸ Edge Style ▸ Wedge shows which way each animal faces.

Fix them: turn on Propagate Track Labels, go to the first frame after the swap, and press Cmd+T / Ctrl+T to transpose the two tracks back.

Lost identities¶

The tracker loses an animal, often when it's hidden or not detected for a few frames, and starts a new track when it reappears. One animal is now split across two tracks, and the project has more tracks than animals.

Find them: Cmd+E / Ctrl+E jumps to the next frame where a track first appears. A track starting partway through the video is usually a break, not a new animal. The track bars on the seekbar show where one track ends and another begins.

Fix them: turn on Propagate Track Labels, go to the frame where the new track starts, and assign that instance to the original track (Cmd+1 … Cmd+9 / Ctrl+1 … Ctrl+9, or Tracks ▸ Set Instance Track). The new track is reassigned on every later frame, joining the two. Then run Delete Unused Tracks to remove the leftover.

Fewer mistakes to begin with

Setting Max tracks to the number of animals when you run inference keeps the tracker from creating extra tracks. See Inference for the tracker settings.

Cleaning up¶

Action	Effect
Delete Instance and Track (`Cmd`+`Shift`+`Backspace`)	Removes the selected instance and every other instance on its track in the current video. The track stays in the project, and other videos are untouched.
Delete Track ▸ …	Removes one track from the project
Delete Unused Tracks	Removes tracks with no instances left on them
Delete All Tracks	Clears every track assignment

Delete Unused Tracks is worth running before export — tracking passes tend to leave behind empty identities that clutter the track list and every analysis file.

Seeing tracks¶

The track occupancy bars on the seekbar show which identities exist when, and where they start and stop.
Cmd+E / Ctrl+E jumps to the next track spawn frame — where a new identity first appears. New identities mid-video are usually a tracking break rather than a new animal, so this is a fast audit route.
View ▸ Apply Distinct Colors To ▸ Tracks colors instances by identity, which makes a swap visible instantly. Predictions are drawn yellow unless View ▸ Color Predicted Instances is on, so turn that on too when proofreading tracked predictions.
View ▸ Show Track Scores displays the tracker's confidence.
Tracks ▸ Seekbar Header ▸ Tracking Score (or Min Centroid Proximity) plots where tracking is likely to have gone wrong — see Navigation.

Trails¶

View ▸ Trail Length draws each instance's recent path behind it. A trail that teleports across the frame is an identity swap; a trail that stops dead is a lost track.