When outdoor conditions are ideal, outdoor thermal cameras can “see” what the eye cannot, even in complete darkness. Problems occur when rain, humidity, and other outdoor conditions bring background temperatures close to the temperature of objects which represent security concern, such as a person entering an unauthorized area.
When background temperatures closely match the heat of a person, many outdoor thermal cameras will blend the intruder into the background until the person becomes concealed. This can happen even when objects are close to the camera itself. Even nighttime applications create difficulties when conditions reduce the temperature contrast between objects in the scene to conceal targets.
In the example at right, a market-leading thermal camera shows how rain has cooled the scene until there is very little temperature differentiation between the person and the background. Under these conditions, most thermal cameras are unable to distinguish between objects in the foreground and the background due to the lack of temperature variation. The result is a blurry image that conceals the person walking, leading to a gap in security.
This is similar to what we experience when someone wearing white clothes walks in front of a white building. When there is little visible contrast between the edges of a person and background, the person looks blurry or even “disappears.” Likewise, when environmental conditions from rain or humidity create a uniform temperature across the scene, most thermal cameras will miss the intrusion entirely.
Achieving Success with Outdoor Thermal Cameras
The key for the successful use of outdoor thermal cameras is to provide a good clear image day and night. This is achieved with image processing that emphasizes the small variations between objects and the background to exaggerate the fine details and present a clearer image in contrast to other image features. When proper technology is applied, necessary details can be achieved without augmentation from visible cameras, returning the value of thermal imaging for outdoor twenty-four hour use.
In the example below, Clear24 image processing is used to intelligently exaggerate the small differences in temperature caused by the rain. In the Clear24 image at right, the person is clearly revealed, along with scene details like the mailbox, circular driveway and street lamp. The market-leading thermal camera on the left lacks image processing and cannot exaggerate small temperature differences between the person and background.