Interview of 2019 for Pixel guide edited by AN2V (French agency for video surveillance)
Choosing the right pole and bracket is essential for the success of your video surveillance project.
Video surveillance has been widely deployed for many years now not only in city areas but also in industrial or so-called « sensitive » sites.
When video surveillance business started, it seems that the choice for the mounting of the camera was sometimes neglected.
But today, purchasers pay great attention to the selection of the right mounting for the cameras.
Whatever the camera quality, if the mounting wasn’t carefully selected, they are consequences on image quality. A strong blowing wind might indeed have a negative impact on the use of filmed video. Many users already had to deal with this kind of problem.
Why do the mast oscillations impact the quality of the images from video surveillance?
Jean-marc PELARDY, TECHNIMAST Managing Director answers :
Oscillations at the top of the mast are quite natural. They result from several combined factors.
First factor : due to the ground motion, the mast will oscillate alternatively from a central steady position to a flex position on each side of this central position.
The distance between steady and flex positions is called the misalignment in the technical jargon
Directly resulting from the nature of the mast and the wind speed it withstands, it is measured (in mm).
Second factor : to this misalignment, is added the frequency of oscillation. Called fundamental frequency of oscillation, it can be measured in hertz.
These two values, misalignment and frequency, are mainly responsible for the problems of the cameras at the top of a mast where they are accelerated. This is not compatible with the stability constraint.
What can be done to reduce this problem ?
It depends as all sensors don’t need the same constraints. Fixed or dome cameras for example will be more sensible to accelerations and vibrations. That’s why the camera bodies have to take into account these criteria by complying with standard EN 60068-2-6. As to thermal cameras, the image processing software will rather be sensitive to pixilation variation. In this case, the misalignment is to be controlled. Of course the closer you need to zoom, the more stabilized the mounting needs to be.
Each situation will determine the selection of the camera, the focal lengths and consequently the criteria before determining the right mast dimensions for the application needed.
Are City lighting poles adapted to surveillance video ?
Most of the time, they are not. The higher the pole, the less adapted it will be.
This is the reason why, when it’s windy, many cities problems with the image quality.
City lighting poles have to comply with EN40. This standard limits the misalignment at the top to no more than 5 % of the pole height. Whereas the prior criterion for the video is a misalignment not exceeding 1 %.
Cities councils of course have to control the budget and they avoid extra expenses in civil engineering by using existing poles. Unfortunately, it may happens to be the wrong solution as the results are not up to the investment.
We at TECHNIMAST are used to say that if lighting and video are meant to be on a same pole, better choose a video mast rather than a lighting mast.
As a matter of fact, we more and more manufacture « mixed » masts.
Is stability the one criterion for video ?
Of course not ! When you make a study for a video masts, many elements have to be taken into account. Let me give you some examples :
·The aesthetic of the global mast+camera assembly, must be thought to be well integrated in the future environment.
· Only a mast visit door with the right dimension will ease and secure the integration of the camera electronic device.
· A high security mast when to be installed in sensitive areas.
· Think about the access to the camera for service operation
The fact that many subjects are common to almost all situations, has enabled Technimast to develop since 2012 standardized products. In the same time, we deal every day with specific cases and assist / advise our customers to get the most accurate solutions.
As a conclusion, keep in mind that a successful video deployment requires as much rigour in the choice of the mounting as for the electronic part of the project. »