XR object tracking subsystem

The object tracking subsystem attempts to detect three-dimensional objects in the environment that have previously been scanned and stored in a reference objects library.

Terminology

Term	Description
Reference object	A reference object is a previously scanned object. The object tracking subsystem attempts to find instances of the object and report on their poses.
Reference object library	A set of reference objects. When you start an object tracking subsystem, you must first provide it with a library of reference objects so it knows what to search for.
Provider	The object tracking subsystem is an interface which is implemented in other packages. Each implementation is called a "provider". For example, you might have a different provider package for each AR platform.

Creating a reference object library

You create reference object libraries in the Unity Editor, then fill it with reference objects. Each reference object requires a provider-specific representation for each provider package you have in your project.

From Unity's main menu, go to Assets > Create > XR > Reference Object Library:

This creates a new Asset in your Project. To create reference objects, select this Asset, then click Add Entry:

Reference objects have a Name, followed by a list of provider-specific entries. In the example above, the object only has one entry for ARKit.

You need to populate the reference object entries with provider-specific assets. For instructions on how to do this, refer to the provider's documentation.

Using the library at runtime

To use the library at runtime, set it on the subsystem. For example:

XRReferenceObjectLibrary myLibrary = ...
XRObjectTrackingSubsystem subsystem = ...

subsystem.library = myLibrary;
subsystem.Start();

Note: You must set imageLibrary to a non-null reference before starting the subsystem.

Query for changes to tracked objects with XRImageTrackingSubsystem.GetChanges. This returns all changes to tracked objects (added, updated, and removed) since the last call to this method.