Perimeter intrusion or areas too large to illuminate
This is often the case with border applications, nuclear and hydro power generation, refinery perimeters and airports.

Situations where lighting is unwelcome
In situations where lighting can offend local residents or where it might draw unwanted attention to your facility, thermal imaging cameras allow for covert operation.

Long-range detection
Thermal energy travels through many atmospheric obscurants better than visible light, making it ideal for detecting activity at extreme ranges.

Applications that require more information than the eye can see
Thermal imaging can provide scene information that isn't always visible to the naked eye, like open windows or recently parked vehicles.