EN 62676-4 splits CCTV requirements into four operational levels, each with a pixels-per-metre (PPM) target. Specify the level, derive the PPM, calculate the focal length. Skip this discipline and you have hours of footage that prove nothing.
Four ideas to carry into the next specification conversation you have.
Four operational levels. PPM thresholds (per EN 62676-4): 25 / 62 / 125 / 250 pixels per metre on target.
A 4K (3840 px wide) camera covering an 8 m doorway gives 480 PPM, easily "identify" class. Same camera at 30 m: 128 PPM, only "recognise."
A wide-angle lens shrinks faces. "More coverage" at 90° FOV typically gives 70% fewer PPM than at 30° FOV. Choose lens for use, not for spec sheet.
H.265 over H.264 saves 50% bandwidth at the same quality. But low-bitrate compression smears faces. Spec minimum bitrate, not just codec.
Per EN 62676-4 / IEC 62676-4. PPM measured on target plane.
| Level | Min PPM · subject height in px | Use case |
|---|---|---|
| Monitor (M) | 12 PPM · 25 px | Crowd flow · perimeter heat-map |
| Detect (D) | 25 PPM · 50 px | Intrusion detection · zone armed |
| Observe (O) | 62 PPM · 100 px | Activity awareness · tagging |
| Recognise (R) | 125 PPM · 200 px | Recognise a known person |
| Identify (I) | 250 PPM · 400 px | ID an unknown person from footage |
| Inspect (X) | 1,000 PPM · 1600 px | Forensic facial detail · birthmark |
Five facts the camera salesperson didn't mention.
An 8 MP camera covering a 50 m parking lot gives ~75 PPM, observe class only. The same camera on the entry door at 5 m gives 760 PPM, easily Identify. The lens, the mounting, and the scene matter more than the sensor.
A 4K H.265 stream at 4 Mbps holds 30 days in 1.3 TB. The same 4K stream at 8 Mbps doubles that. Spec storage on Cisco-grade VMS calculators (Milestone XPM, Genetec Stratocast) before sizing the recorder.
A 1/1.8" sensor at f/1.6 captures 4× more light than a 1/2.8" at f/2.0, same megapixels. For night-time parking, port entry, or unlit perimeters, check the lux rating at colour mode (≥ 0.1 lux for premium) before the resolution.
PDPL (Personal Data Protection Law) came into force 2023. Identifying-class CCTV at workplaces and public spaces requires a privacy impact assessment and signage. Spec a system that supports masking, retention controls, and audit logs, not just pixels.
Wide Dynamic Range (WDR ≥ 120 dB) lets a camera see both a face inside a doorway shadow and the licence plate of a car in midday sun outside it. Without WDR you get the silhouette or the plate, never both. Spec WDR explicitly on every threshold camera.
We design CCTV systems against EN 62676-4 DORI targets, with WDR > 120 dB at thresholds, PDPL-compliant retention, and ONVIF-certified hardware.
Practical lighting know-how from NLC Academy. No spam, unsubscribe anytime.
By subscribing you agree to receive NLC emails.