Test if bounding box anchor falls within polygon ROI

Use This When

• Building zone intrusion detection for security or safety monitoring
• Implementing production line quality checks where items must stay in designated areas
• Creating retail analytics that count people entering specific store regions
• Filtering detections to only process objects within areas of interest

What It Does

• Tests if bounding box anchor point (center or bottom) falls inside polygon region of interest
• Returns boolean indicating containment for rule-based filtering or alerting
• Uses OpenCV point-in-polygon test for arbitrary polygon shapes
• Configurable anchor mode: center for general containment, bottom for ground-plane zones

Works Best With

• Object detector/tracker → this component → conditional branching or alert triggering
• Multi-zone monitoring where different regions trigger different downstream logic
• Integration with detect-zone-transition to track entry/exit events over time
• Feeding evaluate-expression to combine multiple containment tests into complex rules

Caveats

• Polygon vertices must be in correct winding order and form valid closed polygon
• Coordinate systems must align between detections and ROI definition; verify scaling
• Anchor mode choice affects behavior: center for general containment, bottom for floor zones
• Border cases (exactly on edge) are considered outside; add margin if needed