Definition
A hazardous zone is a designated area of a plant where being present carries increased risk - a machine's working envelope, a forklift route, the vicinity of a furnace, an area of work at height. In a vision system the zone is a polygon drawn on the camera image, with a rule attached: who may be inside it and when.
How a zone is defined in the system
The zone is drawn directly on the camera view, not on a building plan. That distinction matters: the system evaluates an image, so the boundary must be visible from that particular camera's perspective.
Conditions are attached to the polygon: hours of applicability, required protective equipment, permitted dwell time, exceptions for maintenance work. Without conditions the zone raises an alert on every passage.
Common deployment mistakes
The most frequent is a zone drawn too wide. It then covers a technical walkway used dozens of times a day, and after a week operators stop responding to the reports.
The second is the absence of time exceptions. If a maintenance crew works in the zone at six in the morning and the system does not know it, the alert repeats through the whole shift and loses meaning.
How it differs from a light curtain
Light curtains and pressure mats are parts of certified machine safety systems: they react immediately and carry a defined safety integrity level.
Vision detection works earlier and wider: it sees the approach rather than the crossing, and covers areas that cannot be fenced. It does not replace certified systems, it complements them.
Frequently asked questions
How many zones can one camera have?
In practice as many as the view covers and operations justify. The limit is computing capacity across concurrent scenarios, not the number of polygons.
Do zones work at night?
Yes, provided the area is lit or the camera works in infrared. In complete darkness vision detection does not work; that is a limit of the method, not of a particular system.
Does the system tell a worker from a forklift inside a zone?
Yes. Detection classifies objects, so the rule can be set separately for people and for vehicles.