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The Three Primary Technologies for Night-time Video Surveillance White Paper Download |
There are lots of challenges in performing video surveillance at night. The optimal solution for a particular application will depend on the requirements for the specific application. For example, is daytime operation required? Does the system need to be covert (so that no visible illumination is used so that it is either undetectable or limits light pollution)? What is the size and shape of the area to be monitored? Is the goal of the surveillance to detect, recognize or identify subjects in the field of view? The "best" system design for a specific video surveillance system that includes imaging at night will utilize one of the three primary night vision technologies: low-light imaging, thermal imaging and near-infrared illumination. In this article, these three technologies are explained and the advantages of each reviewed. As shown in the figure below, each night vision technology exploits a different range of the electromagnetic spectrum. Low-light imaging devices basically work in the visible light range, normally 400-750nm. Near-infrared illumination operates in the non-visible near-infrared spectrum, wavelengths slightly longer than visible light. Thermal imaging operates in the infrared range of wavelengths, normally 3-5μm or 8-12μm.
The table below summarizes some of the differences in the technologies.
Key: +++ - Best ++ - Good + - Marginal o - Poor
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