Positional Device Tracking Regression?

Conditions:

- Vuforia: v8.3.8

- Unity: v2019.1.14f1

- Runtime Platform: iOS

- Positional Device Tracker: Active

- FusionMode: FusionProviderType.PLATFORM_SENSOR_FUSION or ALL

- World Center Mode: DEVICE

In the above conditions, the tracking of images targets is jerky and erratic. This is especially noticeable when the target is moving and not stationary.

This can be seen in the Vuforia Samples by making two changes to the 3-ImageTargets scene:

1. Set the ARCamera "World Center Mode" to "DEVICE"

2. Enable the Device Tracker on the "Trackable Settings" Component or just enable it at runtime through the built-in settings.

Previous versions of Vuforia did not demonstrate this behaviour using FUSION_OPTIMIZE_IMAGE_TARGETS_AND_VUMARKS. (no longer available).