Why many video cameras do not serve their purpose
Network video cameras are now an integral part of security in many businesses. Video technology is now so sophisticated that situations and people can be recorded in detail, even in poor lighting conditions. But many cameras fail to serve their purpose or are even unusable.
A video camera is mounted on a wall in front of a store. But what does it actually record? The surroundings, the street or the entrance area? For what purpose was it installed? If these points are not precisely defined, the camera often fails to serve its purpose. "Then, in the end, it's just some camera looking in some direction at some place and recording something. So the result is a random product. And unfortunately, I have the feeling that I often have to deal with random products," explains Roland Bachofner, image forensic expert at the Zurich Forensic Institute.
Lack of knowledge prevents optimal adjustment possibility
Image forensics examines image material for everything that can be measured on humans. This includes facial recognition, measurement of body mass, comparison of clothing or analysis of movement details. If a camera is incorrectly set or adjusted, it may not be possible to clearly capture all of these details and thus the images cannot be used. According to Bachofner, the resolution of the camera is not the decisive factor, as is often assumed. What matters is the pixel density in the protection target. This means that the pixel density must be highest at the point to be monitored, for example at the entrance to a store or in front of a display case in a museum. The resolution is always the same over the entire image, but the density changes with increasing distance. The user can fine-tune this via the focal length.
"My experience is that camera systems are getting better and better and can reliably capture situations and people in detail. However, considerable deficiencies emanate above all from the handling during operation. Video surveillance systems are very often not used to their full extent due to a lack of knowledge about the optimal setting options and thus miss their target completely," Bachofner continues.
Camera technology is also crucial
Contrast, light sensitivity, noise behavior and color reproduction are essential elements of a good video image, but they also require enormous computing power.
Users often do not know the camera systems and the technology behind them in detail and therefore do not know exactly what they are to be used for. People trust that the camera can do "that". "Too small, too far away, or too dark - these are my standard answers to questions about objects in image captures," confirms Bachofner. So when mounting and setting up a camera, the user must ask himself what is to be recorded in the first place. To do this, certain requirements must be specified. For each application purpose as well as each protection goal, the following properties should therefore be conscientiously checked:
- Level of detail
- Shooting angle
- Contrast behavior
- Light sensitivity
- Noise behavior
- Color fastness
- Forensic evaluability
- Avoidance of motion blur
Only when these points are precisely defined are cameras of use and their video images ultimately usable. When a camera's capabilities are optimally exploited, this not only facilitates the work of an image forensics expert, but also supports the operator, the police or other public institutions. Only in this way can video cameras fulfill their intended (protective) function.
Source: Axis, Schwartz Public Relations
