What is IoU in object detection?

Updated May 15, 2026

Short answer

IoU measures overlap between predicted and ground truth bounding boxes.

Deep explanation

IoU = area of overlap / area of union. It evaluates detection accuracy.

Real-world example

Evaluating pedestrian detection in autonomous cars.

Common mistakes

  • Ignoring IoU thresholds in evaluation.

Follow-up questions

  • What is a good IoU threshold?
  • How is IoU used in NMS?

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