The spectrum of visible light is actually only a small part of a large band of detectable signals, or waves, that travel through matter. The electromagnetic spectrum contains radiation from various invisible wave types, each with a unique wavelength. Thermal radiation is one of these, featuring longer wavelengths than those of visible light, and is therefore generally invisible to the human eye.
Any object with a temperature above absolute zero emits a detectable amount of radiations. The higher an object’s temperature, the more radiations are is emitted. Taking advantage of the temperature differences between objects, thermal cameras make the invisible thermal radiation “visible” in the form of heat zone images.
The image reproduction of thermal cameras is not affected by lighting conditions - either extremely low light or even no light at all. And compared with imaging with visible light, thermal cameras are much less impacted by weather conditions such as fog, smog, rain and snow, so that they can work in virtually any environment, anytime.
Video Content Analysis
Thermal imaging has an intrinsic advantage for video content analysis (VCA) – it renders objects with clear outlines that stand out pretty well against the background, even at great distances. Users can easily set up VCA rules to detect actions such as line crossing, intrusion, region entrance, and region exit with high accuracy.