How Thermal Imaging Works

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How Thermal Imaging Works

thermal spectrum

Thermal cameras make pictures from heat, not visible light.

Thermal cameras are an array of heat sensors to make up thermal pixels in a thermal image. These thermal cameras are also known by various other names such as thermal sensor, heat vision camera and thermal vision camera.

Thermal Cameras have unlimited applications because Thermal energy is radiated from everything.  Thermal cameras can capture temperature differences emitted from;

  • Living things – People, animals and vegetation.
  • Buildings – Skyscrapers, buildings, factories, houses and tents.
  • Machinery – engines, conveyor belts and assembly lines.
  • Planes, Boats and Vehicles – all types of automobiles, boats and vehicles
  • Electrical – circuits, power lines, capacitor, coupling capacitor and insulation etc.
  • Land, rocks and buoys – These absorb heat from the sun during the day and radiate it off during the night.
  • Liquids and gas – these all emit thermal radiation and detected by heat vision cameras.

There are many factors that differentiate thermal cameras on the market today, but the most important characteristic is the number of sensors, or thermal pixels.

The number of pixels determine the smallest resolvable object at a given distance and field of view. Obviously the lowest resolution of 160x120 will not see the same level of detail as seen by the higher resolution sensor 640x480 at a given distance.

thermal resolution

Adding visible camera overlays to a very low resolution thermal image can give the appearance of a significantly higher resolution, however, in total darkness  there is no image from the visible camera and you are simply left with heat signatures from the objects in the field of view.  As seen in this Mercedes thermal camera, 640x480 resolution finds a cyclist and his dog in complete darkness.

see pedestrians in thermal image

This is why you should always invest in the highest thermal resolution you can afford and not be fooled by visible camera overlays giving the appearance of higher resolution during daytime from the lowest resolution thermal sensor.

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