Principally every camera has a blind spot, caused by the height and the point of view of the installed camera until it visually reached the floor. Depending on the lens and focal distance this detection free zone is smaller or larger. A thermal image camera with a 35mm lens on a 5m pole a detection free zone of up to 64 m can occur. Considering these zones through intelligent planning they can be eliminated. Therefore two basic scenarios have to be examined:
Surveillance cameras lined up in a row and corner areas in a perimeter course that have to be covered.
This problem can be solved by appropriate camera positions and through additional sensors that cover the gaps.
The solution for item 1 is easy. The camera position is arranged in a way so the thermal camera or day/night camera overlaps the range of vision by the factor “detection gap”. If there has to be a second detection medium, the use of special PIR-detectors can be recommended, installed on poles and able to look backwards for a small distance.
Special attention has to be given to corners. Often there are approaches like picture 1. This is possible at large or very small angles at the fence course when the visibility of the surveillance camera still covers the dead angle of the camera in front. At angles of ± 90° and a security camera with a narrow visibility (9° or 13°) the detection zone is not enough, to cover the length of the detection free zone. This should be handled differently. In each case two cameras have to point into the corner to get a completely detected field (picture 2)
Surveillance cameras lined up in a row and corner areas in a perimeter course that have to be covered.
This problem can be solved by appropriate camera positions and through additional sensors that cover the gaps.
The solution for item 1 is easy. The camera position is arranged in a way so the thermal camera or day/night camera overlaps the range of vision by the factor “detection gap”. If there has to be a second detection medium, the use of special PIR-detectors can be recommended, installed on poles and able to look backwards for a small distance.
Special attention has to be given to corners. Often there are approaches like picture 1. This is possible at large or very small angles at the fence course when the visibility of the surveillance camera still covers the dead angle of the camera in front. At angles of ± 90° and a security camera with a narrow visibility (9° or 13°) the detection zone is not enough, to cover the length of the detection free zone. This should be handled differently. In each case two cameras have to point into the corner to get a completely detected field (picture 2)
 Picture 1 |  Picture 2 |
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