Evoke can track multiple, identical objects. This is similar to proximity-based tracking (see Use proximity-based tracking in the Vicon Evoke User Guide) where multiple instances of a template object can be tracked, but rather than using unique objects to assign template instances to create template objects, object instance tracking randomly assigns the template instances to the corresponding template objects.
For more information, see:
When to use Object Instance Tracking
Use Object Instance Tracking when the following conditions apply:
- You have multiple, identical physical objects.
- You don't require a guarantee that object assignment is the same frame-to-frame.
- You aren't able to use proximity grouping to derive the identity of duplicate objects from nearby unique objects.
- You are not reliant on functionality that requires consistent frame-to-frame assignment either within Evoke (eg, motion-model switching, one-euro filtering, Low Jitter mode), or in external software.
Don't use Object Instance Tracking if any of the following are true:
- You only have a single object to track.
- You need to uniquely identify multiple objects.
- You are not able to generate identical physical objects.
How to set up Object Instance Tracking
To set up tracking of multiple identical objects:
- Create multiple identical objects as needed. The workflow varies, depending on the type of objects you need to create:
- For smart objects:
- Create as many objects as are required.
From the Settings menu, select Preferences and in the User Preferences, go to the Objects section and clear Automatically manage smart object patterns.
Set the same pattern on all the objects used for instance tracking.
- For basic objects:
- Create a single object from selected reconstructions (Tracking Setup panel > Basic Object line > Create button, or for details, see Create basic objects).
- Export this object by going to the Tracking panel, right-clicking on the object, then selecting Export.
The object is exported as a VSK.
- In Windows Explorer, create multiple copies of the object VSK and name them appropriately.
- Import these objects (at the top of the Tracking panel, click the Import object button ).
- For smart objects:
- In the Tracking panel, go to the Properties pane and ensure the Advanced properties are displayed .
- In the Proximity Grouping section, set the Template Group Name for these objects to the same (non-empty) name.
- In the Processing panel, display the Advanced properties , go to the Proximity Grouping section and select Enable Object Instance Tracking.
When the system detects an instance of this template group that has not been labeled, it randomly assigns one of the (currently untracked) objects in that group to the instance.
Where possible, these identities are preserved during frame-to-frame tracking. If tracking is lost frequently such that object identities change, it may be advisable to avoid using features that rely on temporal information (such as one-euro- and motion-model-filtering, DataStream-retiming and, potentially, Low Jitter mode).