Surveillance and Monitoring Systems
Domain 3 - Surveillance and Monitoring Systems. This domain tests whether you can specify cameras and monitoring procedures by purpose rather than by megapixel count: detection, recognition, identification, or general situational awareness, each with its own pixel density, lighting, retention, and response requirements.
Core rules
- Define the purpose first. Detection, recognition, and identification need different pixel densities across the field of view. Megapixels alone do not guarantee usable images.
- Pixel density is resolution across the scene, not total sensor pixels. A wide field of view spreads pixels thinly; narrow the view or move the camera closer to gain detail.
- Lighting matters: check lux, dynamic range, glare, and low-light performance. Wide dynamic range helps at entrances; infrared helps only where its range and reflection are controlled.
- Video management must support time synchronization, retention policy, export with hash or audit trail, and access control to recordings. Evidence handling requires chain of custody.
- Monitoring is a human system: alarm queues, operator procedures, escalation, fatigue limits, and privacy law all affect effectiveness.
Worked example
A 1920-pixel-wide camera covers a 12 m entrance width, giving about 160 pixels per metre. That may support recognition of a person but not reliable facial identification. The designer should narrow the field of view, add a second camera at the door, or move the camera closer, then verify with a test image at the actual lighting level. Adding megapixels without changing the scene geometry may not solve the problem.
Traps
Equating megapixels with pixel density; recording but never monitoring or responding; retention shorter than investigation needs; unsynchronized clocks; and ignoring privacy or signage requirements.