Dock door utilization tracking from the yard camera

At 6 am the yard has twelve doors and a clipboard. The gatehouse writes down which trailer went to which door and when, the dock lead walks the apron twice a shift and updates it, and by mid-afternoon the sheet and the yard disagree about at least two doors. A carrier phones to ask how long their trailer sat at door 9 on Tuesday, and the honest answer is that nobody knows within an hour.

The yard camera on the corner of the building has been looking at all twelve doors the whole time.

Object detection finds the trailer, the geometry finds the door

The model's job is smaller than it sounds. It boxes trailers, and it boxes the door number markers painted above each door. Trailers are large and distinct and a detector handles them from the first version, on all twelve doors including door 12 at the far end of the frame. Door numbers are small, sometimes in shadow, sometimes behind the corner of a trailer, and they are the part that takes a person's attention at labeling time, because a door number the model never boxes is a door that can never be reported.

Tying a trailer to a door is geometry, on a fixed camera. Each door number box is widened sideways by a margin the dock lead sets once, and a trailer whose box overlaps that widened region belongs to that door. Object detection supplies the boxes and the rule supplies the meaning, and the rule is written down where somebody can change it when the yard is repainted.

The warehouse spatial mapping use case is the same idea at floor scale: fixed cameras, boxes on the things that move, and a rule that turns position into a state.

Occupied is a state that has to hold across frames

A single frame with a trailer over door 9 does not make door 9 occupied. A truck backing in crosses three door regions on its way to the fourth. A yard tug passes along the apron. A trailer parked at an angle overlaps two markers at once. If every frame flips the state, the record is noise.

So the state persists. The camera is sampled about every two seconds, and a door becomes occupied when the overlap has held for long enough that a truck could not still be manoeuvring, and empty when the trailer has been gone for the same span. What gets recorded is the change, with its time: door 9, occupied, 6:42. Door 9, empty, 9:15.

That is the whole ledger. Everything the dock manager wants is a query over those rows.

Dwell time per door is what the dock manager actually reads

The record of changes gives a dwell per visit, and dwell per door over a week is the number the yard has never had. Door 9 averages three hours because it serves the slowest pick area. Door 2 is empty for most of the afternoon while trucks wait at the gate. Neither is visible from the clipboard, and both are visible from the first week of frames.

The question is asked of LexInsight in plain words: which door had the longest dwell this week, and what was at it. The answer comes back with the times and the frames, which is the part that settles the argument with the carrier. A dwell figure with the picture of the trailer behind it is a different conversation from a dwell figure on its own.

The dock lead still walks the apron. What changes is that the walk is to fix what the camera showed, and not to find out what is there.

The door number is read from the frame, and checked against the list

The marker box gives a region, and the number inside it has to become text so that the report names door 9 rather than a marker at the left of the frame. That read is a question asked of the frame, and the answer is checked against the list of doors the yard actually has. A read that comes back as a door that does not exist is held for review, and a read that flips between two neighbouring numbers on a door that has not changed is held too.

Door 7's number is painted on the tarmac in front of the door as well as above it, and the tarmac copy is covered by the trailer the moment the trailer arrives. The marker above the door is the one the rule uses.

Rain and glare are the mornings the numbers go unread

The failure that arrives on its own schedule is weather. A November morning with rain on the lens, low sun off the wet apron, or fog that sits until ten, and the trailer boxes hold while the door number reads fall away for a few hours. The frames from those hours come back to a person as doubted, which is the right behaviour, and the wrong response is to dismiss them as a bad morning.

The drift catalog treats this as rain, fog and dust: a transient shift that arrives and leaves, and is dismissed as noise precisely because it leaves. My own view is that the rainy frames are the most valuable labeling window the yard will get all year. A few dozen of them, boxed by the dock lead on a quiet afternoon, and the next version reads the markers through the next front.

LexData takes the dock model through its whole life. You type what to look for, Lexi puts a box on every frame, and a person checks each label before anything trains on it. The model then watches the yard camera the warehouse already has, in the cloud, on your servers, or on a runner beside the recorder. Frames it is unsure of come back to a person, the corrections retrain it, and the new version replaces the old one with no downtime.

The alert is a trailer at a door past the dock's tolerance

Once the state and the dwell exist, the alert is a sentence: a trailer at any door for longer than the tolerance the dock sets, routine, to the dock lead's channel, one message per door per visit. It is approved before it goes live and it arrives with the frame, the door and the time the trailer landed. The alert written as a sentence is what gets a stalled door in front of someone who can send a forklift, and the ledger underneath it is what tells the carrier, to the minute, how long their trailer sat at door 9 on Tuesday.