Open Radar

 
Area:
Vision.framework

Summary:
When running a VNTrackRectangleRequest on a VNRectangleObservation that has been manually created (using one of the provided initializers), the VNRectangleObservation output from the tracking request has an incorrect bounding box.

I've attached a slightly modified version of the sample code TrackingMultipleObjectsOrRectanglesInVideo, found here: https://developer.apple.com/documentation/vision/tracking_multiple_objects_or_rectangles_in_video

My changes can be found on line 68 of VisionTrackerProcessor.swift.

Steps to Reproduce:
Create a rectangle observation: VNRectangleObservation(boundingBox: myCustomBoundingBox)
Creating a VNTrackRectangleRequest with the rectangle observation
Observe the bounding box property of the VNRectangleObservation output when the tracking request has completed.

Expected Results:
The tracking request is able to accurately track a given rectangle across several frame.

Actual Results:
The tracking request outputs an incorrect bounding box, and therefore is not able to track the next frame with that previous output.

Here is the debugger output of a rectangle observation before being fed into a tracking request, and then the rectangle observation that is returned as the output of that tracking request:

<VNRectangleObservation: 0x280ca55f0> 08D44526-469F-4CA0-929D-6C69ABC29180, revision 1, 1.000000 [0.308167 0.377704 0.375584 0.215798]

<VNRectangleObservation: 0x280ca4b40> 08D44526-469F-4CA0-929D-6C69ABC29180, revision 1, 1.000000 [0.0125 0.0125 0 0]

You can see that the UUID is the same, but the bounding box changes to a completely incorrect [0.0125 0.0125 0 0].

Version/Build:
Xcode Version 10.1 (10B61)
Deployment Target 12.0

Configuration:
iPhone 7
iOS 12.1.2 (16C104)