Night vision surveillance keeps a camera useful after dark. Infrared illuminators light a scene the eye cannot see, low-light sensors gather what light remains, and thermal cameras read heat instead of light. Each has a range limit and its own failure mode.
Night is when most sites need coverage and when cameras perform worst. The choice between infrared, low light and thermal should follow what has to be seen.
Infrared and low light
Infrared gives a usable monochrome image in total darkness but falls off with distance and reflects off rain, dust and spider webs. Low-light sensors keep color further into the evening but still need some light.
Thermal is different
A thermal camera detects temperature difference rather than visible light, so it works in complete darkness and through light fog. It shows people and vehicles clearly but cannot read a face or a plate.
Related:Glossary: Non-infrared day/night cameraCommercial security camera systems