Problem with minimum matching threshold parameter of ByteTracker

[rsnk96]

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• I have searched the Supervision issues and found no similar bug report.

Bug

Hi folks. Amazing project, but I'm getting a peculiar behaviour in ByteTracker.

My assumption for the minimum_matching_threshold parameter of ByteTracker is that it acts similar to an IoU threshold. A smaller threshold should make boxes match more easily, and a larger threshold should make boxes match only if they have a really good match score (ex: really high IoU). However, I observe the inverse behaviour. Not sure if this is expected, but thought I'll highlight it here

Environment

• Supervision: 0.25.0
• Ubuntu: 22.04
• Python: 3.10

Minimal Reproducible Example

Code block to reproduce:

import supervision as sv
import numpy as np

detections = [sv.Detections(xyxy=np.array([[10, 10, 20, 20]]),class_id=np.array([1]),confidence=np.array([1]))]*2
detections+= [sv.Detections(xyxy=np.array([[11, 11, 21, 21]]), class_id=np.array([1]), confidence=np.array([1]))]*2   # 90% overlap

byte_tracker_low_threshold = sv.ByteTrack(minimum_matching_threshold=0.1)
tracked_detections = [byte_tracker_low_threshold.update_with_detections(d) for d in detections]
print("Track IDs associated with detections in 10\% overlap: ", list(t_det.tracker_id for t_det in tracked_detections))
print("Internally tracked states in 10\% overlap: ", byte_tracker_low_threshold.tracked_tracks)

print()
print()

byte_tracker_high_threshold = sv.ByteTrack(minimum_matching_threshold=0.9)
tracked_detections = [byte_tracker_high_threshold.update_with_detections(d) for d in detections]
print("Track IDs associated with detections in 90\% overlap: ", list(t_det.tracker_id for t_det in tracked_detections))
print("Internally tracked states in 90\% overlap: ", byte_tracker_high_threshold.tracked_tracks)

Gives the output:

Track IDs associated with detections in 10\% overlap:  [array([1]), array([1]), array([], dtype=int64), array([2])]
Internally tracked states in 10\% overlap:  [OT_1_(3-4)]


Track IDs associated with detections in 90\% overlap:  [array([1]), array([1]), array([1]), array([1])]
Internally tracked states in 90\% overlap:  [OT_0_(1-4)]

I would expect the opposite to be true, i.e. when we set a low minimum_matching_threshold, it should assign the same track ID to detections more easily (with less IoU overlap). However, that doesn't seem to be the case.

Additional

No response

Are you willing to submit a PR?

• Yes I'd like to help by submitting a PR!