Professional design of CCTV system

While designing CCTV systems much time is spent on estimating lens focal length and the right location of video cameras to get the necessary image on the screen. Estimating person identification areas and license plate reading-out areas caused additional difficulties. The task becomes more complicated when it is necessary to choose optimal relative position of several cameras or when it is necessary to make one camera solve several tasks (for example identification of entering people and surveillance over the perimeter. You can also add the frequently arising necessity to calculate how this or that object will be displayed, where the motion detector will detect a person for instance with enough light and contrast ratio and where it will not.It should be considered that not only lens focal length but also height of the camera installation, maximum distance and the height of surveillance have an influence on the screen image. When choosing the wrong camera location and the height of camera installation, even with the replacement of the lens you wouldn###t be able to get the desired image.If we also remember obstacles that distort the viewing areas and dead space under the camera, then we can see the difficulty of the problem put by. And the more difficult the task is the more likely that a mistake will occur. The result of which at best can be project cost increase.These tasks can be solved in different ways:- Someone will accurate calculate the viewing areas for several heights and lens focal length of each camera using self deducted formulas or formulas taken from guide books and then transfer or combine obtained templates.- Someone makes the calculation easier and having introduced reserves gets approximate results with the help of Lens calculator.- Someone draws on the plans only horizontal angles from lens specification thus confusing himself and a customer even more.- And many people ignore such calculations because of their complexity and labour-intensiveness and place wide-angle lenses or the most expensive ones (from the price list of the producer) and then plan to choose the wanted lenses on practice. In the meantime a project of a CCTV system that doesn't show the viewing areas of each camera and its functions in different regions of space can not be considered a professional one.Wide-angle lenses (very often they remain the same even after acceptance of work) as a rule satisfy the needs of a customer only up to the first emergency. After an emergency it comes out that there is practically no use from such a CCTV system. Criminal is not identified, license plate is not read out, motion detector did not detect any movement. Suddenly it comes up that there should be more cameras, their location should be different and lenses should have another focal length. But sometimes a customer accepts a design that does not solve his/her tasks. Such a project does not show what and how each camera is going to see, so a design that doesn't contain the most important information can be approved.The situation looks different if truly professional projects participate in a tender. Having a professional project it is possible to discuss with a customer a task of each camera, choose and substantiate their necessary number. After having done the calculations one may not necessarily need more video cameras because one camera can fulfill several tasks. Such solutions are more time consuming but allow to create effective and at the same time economical projects.But after each discussion and transference and cameras parameters change one has to do recalculation, calculate and compare several variants of cameras placement. Thus professional designing of a television system is a very difficult task that demands much time. But not all customers understand this and it happens that they give preference not to the best project, but to the one that was quickly rendered or to the cheapest one.However all dependences of camera viewing areas obey to the laws of geometrical optics and can be described mathematically. Widely spread are Lens Calculators that can be used on many security web sites on-line and they can be in the form of small programs or a plastic circle. Viewing areas is viewed as a rule in two-dimensional aspect which allows to use relatively easy calculations.Calculators' resources are approximately the same but they are insufficient for professional designing. The most convenient is the plastic circle which can be easily used in field conditions. Calculators are convenient for rapid calculations of viewing field width and height, but they don't allow calculating even the dead space under the video camera let alone full-fledged calculation of viewing areas' projections to draw them on the plan of an object. And calculation of person identification areas and license plate reading out areas is out of question.Having moved to a three dimension coordinate system the complexity of calculations increase many times, therefore it is practically impossible to find a good three-dimensional free calculator.But it is still inconvenient to work with a specialized three-dimensional calculator especially when it is necessary to calculate several connected video cameras. One has to use simultaneously a program-calculator and CAD program, that locates video cameras on the plan, over and over again recalculating and redrawing viewing areas projections in order to get the necessary result.The next step is a integration of a three-dimension calculator and CAD program. The calculator acquires a graphical interface and its calculation results are presented in graphic form. Obtained graphical calculation results are represented directly on the plan of an object in horizontal and vertical projections. Graphical interface that allows to locate video cameras by one mouse click, to raise or lower a video camera only by one turn of a mouse wheel, change its angle of inclination and lens focal length and see the result there and then, all that makes CCTV systems designing an easy and exciting work.Obtained projects have the maximum of exactness, are quick to implement and correct and don't demand from a CCTV systems designer mathematical knowledge and understanding of peculiarities of objects' representation in different parts of viewing areas (although such understanding remains rather useful).A new program for CCTV systems designing has been launched, it is called VideoCAD. The latest version of VideoCAD 3.01 is a full value CAD program integrated with a special three-dimension calculator for calculating cameras' viewing areas parameters. With the help of VideoCAD, a CCTV project can be designed in a short period of time. Specialized calculations of video surveillance (viewing areas, person identification areas, license reading-out areas, detailed representation of objects in different parts of a viewing area, calculation of length and electrical parameters of cables) are tightly integrated with a traditional CAD interface.VideoCAD###s main features include:- Choose the most suitable lenses, heights and locations for camera installation to provide the required parameters of view areas, detect and identify a person, read license plates out and obtain an object image of required size on a display using the known actual sizes and location of an object.- Choose visually a relative location of cameras using the graphics window with CAD interface.Calculate the horizontal projection sizes of viewing, person detecting, identifying and license plate reading-out areas to draw them on the object plan.- Measure the view area distortions, arising from natural obstacles. – Calculate the image size on a display of any object i

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