Thermal vs ANPR vs Covert: Choosing the Right Perimeter Camera

\"Which camera should I put on my perimeter?\" is the wrong question. The right one is \"what am I actually trying to catch?\" Detecting a person crossing a field at night, reading the plate on every vehicle entering a yard, and quietly evidencing a repeat offender who already knows where the cameras are — those are three different jobs, and they need three different cameras. This guide explains what thermal, ANPR and covert cameras each do well, where each falls down, and how UK sites combine them into one layered perimeter. Last updated: June 2026. Start with the threat, not the spec sheet Every perimeter has a primary failure mode. A remote yard or field is about early detection — knowing someone is on the boundary before they reach anything worth stealing. A gated site or car park is about identification — knowing exactly which vehicles came and went, and when. A site plagued by a known, repeat problem (fly-tipping, internal theft, a persistent trespasser) is about discreet evidence — catching behaviour without tipping off the person doing it. Match the camera to that failure mode and the rest of the decision gets easy. Thermal: detection in the dark and the weather Thermal cameras don't see light — they see heat. That makes them the strongest option for long-range detection across open ground, especially at night, in fog, in glare or through light foliage where a conventional camera is blind. A person stands out as a clear warm shape against a cool background at distances a standard lens can't usefully cover. Where thermal earns its keep: Large perimeters — solar farms, reservoirs, substations, quarries, big rural boundaries Conditions that defeat optical cameras: total darkness, fog, smoke, backlighting Pairing with AI analytics so you get \"human-shaped heat source crossing the line\", not an alert for every animal The trade-off: thermal shows shape and movement, not detail. It will tell you someone is there; it usually won't give you a face or a number plate. Treat it as your trip-wire, not your evidence camera. See the thermal cameras range for spec'd options. ANPR: knowing exactly which vehicles came and went Automatic Number Plate Recognition cameras are purpose-built to read and log plates at the point a vehicle enters or leaves. They turn a gate, an entrance lane or a car park into a searchable record: which vehicle, which plate, what time. That's invaluable for yards, depots, car parks and any site where vehicle movements are the thing you need to account for. ANPR works best when: You can control the geometry — a defined lane, a sensible approach angle, the right mounting height and a camera optimised for plate capture rather than a general-purpose lens You want a watch-list or audit trail — flag known vehicles, log everything, export for incidents or billing It feeds a wider system — at a car park, the plate log underpins enforcement and payment ANPR is narrow by design: it's superb at the entry point and largely irrelevant in the middle of a field. For the procurement detail — lane design, mounting, accuracy expectations — see our dedicated ANPR car park procurement guide and the ANPR cameras range. Covert: evidence without tipping anyone off Covert cameras are about not being seen. When the problem is a repeat offender — fly-tipping on the same lane, theft from a specific store, a known internal issue — visible cameras can simply move the behaviour elsewhere. A discreet, well-hidden camera captures what's actually happening and produces evidence that stands up. Covert is the right tool when: You need to evidence a specific, recurring problem rather than deter generally Visible deterrence has already failed or would just displace the issue You're supporting a prosecution or insurance claim and need clean, uninterrupted footage The catch is that covert removes the deterrent effect — you're documenting, not preventing. It's a targeted tool, often deployed temporarily, not a whole-site strategy. See the covert cameras range. How real sites combine them On most serious perimeters these aren't either/or — they layer: Thermal on the open boundary for early, all-weather, all-light detection ANPR at the gates so every vehicle in and out is logged and searchable Covert in the specific trouble spot where you need discreet, prosecution-grade evidence AI analytics across all of it so alerts are real detections — intrusion, vehicle, plate — not a flood of motion noise That layered approach is exactly what the Solution Builder is designed to spec — it walks you through what you're protecting and matches the camera mix to it. Getting the mix right The most expensive mistake is buying one camera type and expecting it to do all three jobs. Tell us what the perimeter looks like, where the real risk sits and how it's powered — most of these run perfectly well off-grid on solar 4G/5G — and we'll spec the right combination. Browse the full 4G/5G CCTV range, start with the Solution Builder, or talk to our UK team. 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