Evaluated on a stream-grouped hold-out split (no frames of a validation stream were used in training). The mAP@0.5 column in the model table shows this same held-out value; models without a stored held-out evaluation fall back to the in-training validator's mAP@[.5:.95], shown greyed out.
Optional. Leave empty to use all footage; set it when assets look different at the current event, so older events do not supply examples.