Fig. 9 Comparison chart between model Loss curve and model mAP value
⑶ P-R curve
The pink, purple, green and gold curves in the figure represent the P-R
curves of pit, wear, snowflake and crack respectively. The P-R curves of
pit completely cover the P-R curves of crack, which indicates that the
improved RetinaNet model has better prediction performance for pit than
that of crack. Wear’s P-R curve intersects with Snowflake’s. Predictive
performance is compared by equilibrium points. The P-R curve of
snowflake has break-event Point (BEP) A, and the P-R curve of wear has
BEP B. Precision at points A and B is equal to recall. Point B is larger
than point A, indicating that the prediction performance of improved
RetinaNet model for wear is better than that of snowflake. The order of
defect prediction performance is pit, wear, snowflake and crack.