A video detection glossary for reading a bid
Reference event and match
A reference event is a human annotation of a qualifying activity, with a camera identifier, a start and an end. A match links a system event to one eligible reference under a written rule. Before scoring anything, define how much overlap or timing error is allowed and how duplicate alerts will be handled. NIST’s ActEV work illustrates why an evaluation needs activity definitions and an explicit treatment of missed detections and false alarms. The calculations below are our editorial conventions for a site pilot. M01 · NIST activity evaluation plan
Recall and precision
Recall asks how many eligible reference events received a match. Precision asks how many scorable alerts did. Suppose reviewers mark twelve qualifying entrances, and a system issues ten alerts, eight of which match distinct entrances under the agreed rule. Recall is 8/12, about 67%. Precision is 8/10, or 80%. The four missed entrances and the two unmatched alerts tell the shift manager more than a single percentage, and a fraction with a zero denominator is undefined.
False alerts per monitored camera-hour
Divide unmatched alerts by the camera-hours that were actually monitored. Two unmatched alerts in eight monitored camera-hours gives 0.25 per camera-hour. A desk staffed for several cameras at once can use that count to understand review workload — provided the test period resembles its working conditions. Record weather, lighting and time of day beside it.
Negative-window false-positive rate
Divide eligible negative windows containing at least one alert by the total eligible negative windows. Pick a fixed window length and decide how to treat activity that straddles a boundary; two alerts in one negative window count once in the numerator. NIST’s time-based false-alarm measure normalizes differently, so write the formula next to the result whenever two suppliers say “false-positive rate.” M01 · NIST activity evaluation plan
Coverage and delay
Coverage is monitored time divided by scheduled time over the cameras in scope. Two cameras scheduled for four hours each give eight scheduled camera-hours; if one loses an hour, coverage is 7/8. Keep the missing hour visible along with any unscorable events. For alert delay, start the clock when the rule first qualifies and stop when the designated recipient or endpoint receives the alert. Record clock alignment, time to acknowledge and any undelivered alert separately.
Retention and search window
Retention tells the buyer how long a specified object is kept — name the object, whether continuous recording, incident, thumbnail or exported clip. The search window tells the investigator how far back a particular search function can operate. Eagle Eye’s Standard Smart Video Search window illustrates the distinction, and its higher editions tie that search to camera retention. V10 · Cloud VMS editions
ONVIF profile and compatible feed
A profile specifies functions a conformant device and client support, with some functions conditional. Record the exact model and firmware and check the intended client. A successful live view establishes one working path — if the purchase is for an event, an audio response or a search, verify that function on the proposed channel as well. M02 · ONVIF profile guide