Security camera placement for commercial sites

Security camera placement starts with what each camera has to capture, not with where it is easy to mount one: decide the level of detail each area needs, then choose the position, height, and angle that deliver it. A camera that detects movement across a parking lot and a camera that identifies a face at a door are different jobs, and the same camera usually cannot do both from the same spot.

This post works through that decision for a commercial site: the four detail levels, what mounting height and tilt do to them, walls and glass, entrances and overlap, and why the plan belongs on a floor plan rather than on a ladder.

Decide what each view has to deliver

The working vocabulary is DORI, from the IEC 62676-4 standard for video surveillance. It defines four levels of detail as pixel densities on the target, in pixels per meter across the scene:

Level	Pixels per meter	What it lets you do
Detect	25	Tell that a person or vehicle is present
Observe	63	See what a person is doing, and characteristic detail such as clothing
Recognize	125	Tell whether a person is someone you have seen before
Identify	250	Identify a person beyond reasonable doubt

Pixel density falls with distance, so each level has a range. For a camera with a sensor 1,920 pixels wide, the common 1080p case, and a 90 degree horizontal field of view, the ranges work out to roughly:

That one chart explains most placement mistakes. The camera that sees the whole lobby identifies faces only in the first 12 or 13 feet of it. Narrow the lens to 45 degrees and identification reaches about 30 feet, but the view covers far less of the room. A sensor twice as wide doubles every distance at the same field of view.

So assign each area its level before choosing a single camera. A workable default for commercial sites:

• Entrances and exits: identify. Every person who comes in should be identifiable from at least one camera.
• Cash points and high-value areas: recognize. Enough to tell who was at the register or the cage.
• Corridors and general floor: observe. Enough to follow what happened and when.
• Perimeter, yards, and parking: detect. Enough to know something moved, and where to look next.

Mounting height and tilt

Height is a trade. A camera mounted high is harder to reach, harder to tamper with, and sees over people and fixtures. It also looks down, and the steeper the angle, the more of every face is the top of a head. A camera tilted down has a dead zone directly beneath it that it cannot see at all, and its useful far edge is shorter than its flat reach.

The practical rule follows from what each level needs. Identification cameras at doors go lower and aim closer to level, so they see faces rather than hair. Overview and detection cameras go high, where their job is breadth and a steep angle costs little. Anything mounted above arm’s reach needs a plan for how the dead zone under it is covered, usually by another camera’s view.

Walls, glass, and what gets in the way

A camera’s field of view stops at the first solid surface, so a floor plan without walls overstates coverage. Glass is the exception that causes trouble in the other direction: a camera sees through a window, but an infrared illuminator behind glass reflects back into the lens at night, and a view that was clear by day turns to glare after dark. Mount exterior cameras outside, or keep the lens flush against the glass with no gap for the reflection.

The obstructions that matter most are the ones that arrive after installation. Shelving, signage, seasonal displays, and a moved partition can block a view that was right on install day, which is why placement is not finished when the cameras go up.

Entrances first, then overlap

Place the entrance cameras before anything else. Every door, including the loading dock and the fire exits, gets a view at identify level, positioned so a person walking in faces the camera rather than passing it in profile. Backlight is the common failure at doors: a bright doorway behind a person turns their face into a silhouette, so an entrance camera needs a lens and sensor that handle a bright background, or a position that keeps the doorway out of the frame behind them.

Then decide where one camera is not enough. Anywhere a single failure would leave a critical area unwatched, the cash office, the server room, the main entrance, deserves overlapping views from two cameras. Overlap everywhere is wasteful. Overlap nowhere means one knocked camera blinds the area that mattered most.

Plan it on the floor plan

Placement decided on a ladder gets decided one camera at a time, with nobody checking the whole. The better order is the plan first: a calibrated floor plan, each camera drawn where it will mount with its real field of view, the walls drawn in, and every area marked with the level it needs. Then check each area against the level it needs, rather than trusting how the drawing looks.

MentatNOC’s camera coverage map is built for exactly that check. Cones are drawn from each model’s datasheet optics at the chosen DORI level, walls clip them, mounting height and tilt produce the dead zone, and zones read PASS or FAIL against the level each area needs. The planned cameras sit on the same plan as the installed ones.

Doing this across 500 cameras

Placement is planned once and then drifts for the life of the site. Cameras get knocked or re-aimed during cleaning, a remodel moves a wall, a new sign goes up in front of a lens, and the drawing that was right on install day stops describing the building. At a single site someone notices eventually. Across dozens of sites, the gap between the plan and the building is discovered when footage is requested.

MentatNOC keeps the plan and the live fleet on one map. A planned camera is promoted to the real device when it is installed, keeping its position and aim, and from then on its pin carries live health. A camera knocked out of position reads as a camera tamper event next to device-down, rather than as a healthy camera looking at a wall. It monitors device health, not video. The platform overview is on the platform page, and you can plan and monitor a multi-site fleet end to end in a live platform demo.

Good placement is a decision about detail per area, checked on a plan before a single camera is mounted, and checked again every time the building changes.