Added new API SetFaceScaleFactor() for face tracking
It configures the scale at which AR objects are displayed relative to the user’s face in a web-based AR experience.
As part of Release 1.7.4 an enhancement has been deployed to Unity build release v.1.7.4-1 with peel-away mode. Enable this feature to allow the object to be displayed even when the user moves the camera away from the marker, the AR object will still remain on the screen. For more information refer 'Build a marker tracking experience'