Thermal imaging uses cameras that “see” heat instead of light. Sometimes referred to as “FLIR” cameras, they produce an image that portrays objects using their temperature instead of their visible properties.
So how does thermal imaging see heat? All objects warmer than absolute zero (-273°C/-459°F) emit infrared radiation in the MWIR and LWIR wavelengths (3µm–14µm) in an amount proportional to the temperature of the object. Thermal imaging focuses and detects this radiation, then translates the temperature variations into a greyscale image, using brighter and darker shades of grey to represent hotter and cooler temperatures, which gives a visual representation to the heat profile of the scene. Many thermal imagers can also apply color profiles to these images, showing hotter objects as yellow and cooler objects as blue for example, to make it easier to compare temperatures in the image.
No Illumination Needed
Most cameras require a light source to create an image. But since thermal energy is naturally emitted radiation, a thermal imager is able to “see” the environment regardless of lighting conditions. This passive technology can be used in complete darkness without the need for an illuminator, making it an extremely covert and versatile solution.
Detect Threats at Long Range
Humans, animals and vehicles are typically warmer than their environment, providing a high contrast that allows for fast wide-angle detection of threats from a much further distance (sometimes up to 50km) than what can be achieved with optical imaging.
This video demonstrates how much easier it is to detect and track people (because of their heat) with thermal imaging.
Consistent Day/Night Coverage
A visible camera’s image quality is dependent on good lighting conditions, and in areas where contrast is poor or dynamic range is too wide, visible cameras can become practially useless. Thermal, however, is completely immune to changes in light, allowing it to see consistently in any lighting environment for true 24/7 day/night imaging.
See Through Smoke & Light Fog
Thermal energy passes through many visible obscurants including smoke, dust, light fog, and light foliage. The comparison image shown here demonstrates how effective this can be when viewing a forest fire.
In addition, the precise temperature differences that thermal imaging detects can sometimes reveal objects underneath the surface of other materials, such as joists behind a wall or items under clothing, since they affect the temperature of the surface material.
The precise temperature sensing capabilities of thermal imaging can be used to monitor critical equipment in areas like datacenters or manufacturing plants to ensure that it remains in a safe operating state, triggering alarms if temperatures exceed set levels.
While thermal imaging has many great advantages, it’s not a perfect or complete solution for every situation. This is why Infiniti believes in multi-sensor systems that can benefit from the multiple advantages of thermal while still providing a visible imaging system that covers its drawbacks. Here are some limitations you should be aware of with thermal technology.
Doesn’t Show Visible Contrast
Thermal imaging relies on contrasting temperatures to clearly define objects, whereas humans are used to using contrasting colors and shadows to see definition in objects. This can make thermal imaging less effective in situations where definition is expected but the surface temperatures of objects are very uniform, such as printed text and images.
Can’t Identify People
Humans also look very different in a thermal image, and lack the shadows and highlights that we use to see the shape of someone’s face in a 2D image. So while thermal makes humans easy to detect, it is not an effective method for identifying individuals.
*Please see our whitepaper on DRI ratings to properly understand what “detection” means in thermal camera ratings.
Can’t See Through Glass
Since glass emits its own heat and is also partially reflective of thermal energy, thermal imaging is unable to see through glass, which means thermal cameras can not see into building or vehicle windows and cannot be mounted inside a window looking out.
Thermal sensors for security purposes are often limited to a resolution of 640×480, which is much lower than most current optical sensors. However, it’s important to know that the types of details detected by thermal and visible cameras are very different; a high level of detail isn’t as critical with thermal cameras.
Every situation is unique, and most require a variety of technologies. Whether your priority is top-of-the-line performance or the most cost-effective solution, we can design a custom surveillance system that is a perfect fit for your project. Get in touch with us today to see what we can do for you.
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