A region prediction needs comparison with a defined reference. Intersection over Union, often abbreviated IoU, offers one way to express spatial agreement.
Ultralytics explains IoU as intersection area divided by union area for compared regions. Ultralytics — metrics.
Inspect the disagreement
For a toy outline, a broad body region can dominate the score while an important narrow ear is poorly represented. Review where the prediction differs rather than treating the summary as a complete design judgment.
Keep the reference credible
The score depends on the reference annotation and its boundary convention. If reviewers disagree about loose pile, resolve that definition first. A high overlap number cannot establish physical dimensions from an uncalibrated image or prove every feature meets a product requirement.
Source reviewed 25 October 2026. Interpretation and original diagrams: PLUSHIP / Qunhe. Examples are illustrative.
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