Most bad CCTV footage was never going to be good, no matter how many megapixels the box said. The camera was aimed at the wrong thing, or mounted in the wrong place, or pointed straight into a headlight. The fix is cheaper than people expect, because it is about where the camera sits, not what it cost.
Start with what you need to prove
Decide what has to be provable after an incident: a face, a number plate, a forced gate, a load leaving the yard. That sets the pixel density and the lens. Choosing cameras first is the most common design mistake.
Pixel density is the number that actually matters. About 20 to 30 pixels per foot lets you detect that someone was there. Forty to sixty lets you recognise a person you know. Eighty to 120 lets you identify a stranger or read a plate. A 4K camera covering a 60 metre street puts fewer pixels on a face than a 4 MP camera covering a six metre doorway.
Shutter speed matters as much. No slower than 1/60 to 1/100 of a second for faces, and 1/250 to 1/500 for moving plates. A camera that smears a running person is not evidence.
Height and angle
Mount identification cameras at about 2.5 to 3.5 metres, and keep the angle shallow. A camera six metres up looking down at 45 degrees records the tops of caps and shoulders. For plates, keep the horizontal angle narrow.
Chokepoints beat open ground. Every person and vehicle passes identifiable points: the gate, the boom, the turnstile, the goods entrance. Cover those tightly and use wide coverage only for context. At a gate, cover both lanes and both the driver and the number plate, because a plate alone cannot settle a driver dispute.
Night, light and the dome problem
Sensor size usually matters more than megapixels after dark, because bigger pixels collect more light. A 1/1.8 inch 4 MP sensor generally beats a 1/3 inch 8 MP sensor at night.
Domes look neat, but the bubble causes infrared reflections and edge softness. Turrets give cleaner night images. A single PTZ camera is not a coverage plan, because with no operator it points the wrong way. Thermal cameras detect heat, not light, so they warn you someone is there but cannot identify a face or plate.
Backlight causes most useless footage. Never aim a camera into headlights at a gate or into the sun. Use WDR on doorways where a bright background meets a dark foreground.
Storage you can actually afford
Storage is arithmetic. At 2 Mbps a 1080p camera writes about 21 GB a day. At 4 Mbps, about 42 GB. At 8 Mbps, about 84 GB. A 16-camera mix at 4 Mbps for 30 days needs roughly 20 TB. Use surveillance-rated drives, not desktop disks. Motion-triggered recording saves space but creates gaps exactly where you need footage, so record continuously on chokepoints.
Good footage is mostly a placement decision, and it is a lot cheaper to get right at commissioning than to re-aim cameras later. If you have cameras and you are not sure what they actually capture at night, a site assessment will tell you.