---
uid: arfoundation-vs-node-on-tracked-objects-changed
---
# On Tracked Objects Changed
Triggers when AR Tracked Objects have changed. AR Tracked Objects can be added, updated, and/or removed every frame if there is an enabled AR Tracked Object Manager in the scene.
*On Tracked Objects Change node, shown with Get Variable*
## Input Data Ports
| Port | Data type | Description |
| :--- | :-------- | :---------- |
| **Target** | [GameObject](xref:UnityEngine.GameObject) | Target GameObject should have an enabled [ARTrackedObjectManager](xref:arfoundation-object-tracking#ar-tracked-object-manager-component) component. If you do not connect this port, this node searches for an enabled AR Tracked Object Manager component in the scene instead, and throws an exception if none is found. |
[!include[](snippets/get-variable-tip.md)]
## Output Data Ports
| Port | Data type | Description |
| :--- | :-------- | :---------- |
| **Added** | [ReadOnlyList](xref:Unity.XR.CoreUtils.Collections.ReadOnlyList`1) of [ARTrackedObject](xref:UnityEngine.XR.ARFoundation.ARTrackedObject) | AR Tracked Objects that have been added. |
| **Updated** | [ReadOnlyList](xref:Unity.XR.CoreUtils.Collections.ReadOnlyList`1) of [ARTrackedObject](xref:UnityEngine.XR.ARFoundation.ARTrackedObject) | AR Tracked Objects that have been updated. |
| **Removed** | [ReadOnlyList](xref:Unity.XR.CoreUtils.Collections.ReadOnlyList`1) of `KeyValuePair` | AR Tracked Objects that have been removed. |