Object tracking
Object tracking locates and follows objects through a series of frames in a video or image sequence. This is done by detecting and localizing objects in a frame, and then determining their position in subsequent frames using the pixel information enclosed within the label boundary.
Your video or image sequence's pixel information is accessed from the Encord server.
Since tracking algorithms propagate labels forward through frames, object tracking only works if labels are made on lower number frame (i.e. near the start of the video).
Ontologies
| Ontology shape | Interpolation | Tracking |
|---|---|---|
| Bounding box | ✅ | ✅ |
| Rotatable bounding box | ✅ | ✅ |
| Polygon | ✅ | ❌ |
| Polyline | ✅ | ✅ |
| Primitive | ✅ | ✅ |
| Keypoint | ✅ | ✅ |
| Bitmask | ❌ | ❌ |
Tutorial
1. Set up, and identify objects
- Before an object can be tracked, it needs to be labeled near the start of the video.
The more instance labels are manually added throughout the video, the better the automated tracking feature will perform.
- Once that is done, click the Automated labelling button in the bottom left corner of the label editor to bring up the options for automated labeling.
2. Configure & run
The 'Tracking and interpolation' section will be open by default - select the object instance you would like to track.
Under the 'Method' heading, select Tracking.
The 'Tracking annotation interval' is where you specify how many frames the object should be tracked for after the last manual label.
'Tracking range' specifies the range of frames in which tracking will take place.
Object tracking example
If a bounding box for Object A drawn on frames 10 and 40. Setting the ‘Tracking range’ [10,40] and the ‘Tracking annotation interval’ to 30 you will get Object A on all frames 10-40.
Setting the ‘Tracking range’ [20,40] and ‘Tracking interval’ to 30 you will get no additional instances of Object A added because the ‘Tracking range’ will miss the annotated object on frame 10.
Setting the ‘Tracking annotation interval’ to 20 and ‘Tracking range’ [10,40] you will get Object A on frames 10-30 and on frame 40 since the tracker will run 20 frames from frame 10 and then stop that track.
The 'Advanced settings' allow you to choose between the Advanced and Standard tracking models. The Advanced model provides higher accuracy, but takes a longer amount of time to run.
Once you are satisfied with the settings click Run tracking to begin tracking the object instances.