Negative value in mAP

[manishdhakal]

I am getting negative one (-1) mAP for the small-scale bbox_mAP_s objects in the logs.

Terminal Output

.......
2023-01-30 11:34:14,556 - mmdet - INFO - 
 Average Precision  (AP) @[ IoU=0.50:0.95 | area=   all | maxDets=100 ] = 0.000
 Average Precision  (AP) @[ IoU=0.50      | area=   all | maxDets=1000 ] = 0.000
 Average Precision  (AP) @[ IoU=0.75      | area=   all | maxDets=1000 ] = 0.000
 Average Precision  (AP) @[ IoU=0.50:0.95 | area= small | maxDets=1000 ] = -1.000
 Average Precision  (AP) @[ IoU=0.50:0.95 | area=medium | maxDets=1000 ] = 0.000
 Average Precision  (AP) @[ IoU=0.50:0.95 | area= large | maxDets=1000 ] = 0.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=   all | maxDets=100 ] = 0.006
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=   all | maxDets=300 ] = 0.006
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=   all | maxDets=1000 ] = 0.006
 Average Recall     (AR) @[ IoU=0.50:0.95 | area= small | maxDets=1000 ] = -1.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=medium | maxDets=1000 ] = 0.003
 Average Recall     (AR) @[ IoU=0.50:0.95 | area= large | maxDets=1000 ] = 0.008
.....

Log File Output

.....
{"mode": "val", "epoch": 27, "iter": 38, "lr": 8e-05, "bbox_mAP": 0.044, "bbox_mAP_50": 0.136, "bbox_mAP_75": 0.018, "bbox_mAP_s": -1.0, "bbox_mAP_m": 0.0, "bbox_mAP_l": 0.046, "bbox_mAP_copypaste": "0.044 0.136 0.018 -1.000 0.000 0.046"}
{"mode": "val", "epoch": 28, "iter": 38, "lr": 8e-05, "bbox_mAP": 0.045, "bbox_mAP_50": 0.135, "bbox_mAP_75": 0.02, "bbox_mAP_s": -1.0, "bbox_mAP_m": 0.0, "bbox_mAP_l": 0.047, "bbox_mAP_copypaste": "0.045 0.135 0.020 -1.000 0.000 0.047"}
{"mode": "val", "epoch": 29, "iter": 38, "lr": 1e-05, "bbox_mAP": 0.044, "bbox_mAP_50": 0.137, "bbox_mAP_75": 0.019, "bbox_mAP_s": -1.0, "bbox_mAP_m": 0.0, "bbox_mAP_l": 0.046, "bbox_mAP_copypaste": "0.044 0.137 0.019 -1.000 0.000 0.046"}
{"mode": "val", "epoch": 30, "iter": 38, "lr": 1e-05, "bbox_mAP": 0.045, "bbox_mAP_50": 0.137, "bbox_mAP_75": 0.019, "bbox_mAP_s": -1.0, "bbox_mAP_m": 0.0, "bbox_mAP_l": 0.047, "bbox_mAP_copypaste": "0.045 0.137 0.019 -1.000 0.000 0.047"}
....

Can someone provide me with plausible explanation for this ??

[Li-Qingyun]

May be there is no small object

[Maenansyn]

I guess you use a COCO-formatted data or something that follows COCO's evaluation metrics: the -1 represents absent categories.

Look here