3. Look to the Future
Always plan for growth, and we’re not talking about adding more cameras, increasing bandwidth or drive space here. That cute little sapling may not impact the perimeter today, but in a few years how is it going to impact the field of view? From your end user’s perspective, landscaping services such as trimming or removing a tree are recurring costs, which are often harder to get approved versus the fixed cost of purchasing the perimeter system in the first place. Additionally, some locations are very restricted about destroying trees after they reach a certain size. At that point the decision to remove it may be out of the hands of the site owner, but they will have to bear the cost of modifying their security system to accommodate the tree.
Sometimes it’s just about asking the correct question. If the current design includes the protection of an open space or makeshift storage yard, take the time to inquire about the future use of the area. Using one or two cameras with a wide field of view to cover an open space won’t be a very effective solution after new storage buildings are placed in that same location during the next fiscal year.
4. Check Your Blind Zones
Every camera has a blind zone. Its size is determined by the camera lens, and the mounting height and angle of the camera. Basic geometry will allow you to determine the effective blind zone of each camera. In simple terms, if you assume a human target, the blind zone begins at the mounting location of the camera. As the person walks away from the camera, the blind zone ends at the point where you can see their entire body in the video. That also explains why a good perimeter design includes both the maximum range and the minimum range for each camera.
This is a pretty straightforward concept when you have one camera following another camera along a fence line. Where most blind zone mistakes occur is when the coverage takes a turn, for example, at the corner of a property. The next camera is often placed directly at the corner, making it very difficult for the previous camera to cover the blind zone of the previous camera. In these cases, the camera may need to be moved away from the fence corner to ensure coverage.
5. Don’t Get Stuck in the Dark
It’s easy to get caught up in the perimeter layout, taking time to evaluate camera locations, lenses and image resolution only to forget all that will change when the sun goes down. In most cases, the limiting factor in coverage occurs in the evening hours. How do you intend to cover the scene in darkness? Will you use some type of illuminant, such as infrared or a visible light source? Or perhaps the choice is a thermal sensor. A camera that can cover a 500-meter fence line during the day may be reduced to 200 meters at night due to the type of illumination being considered. This not only impacts the layout, but obviously has consequences in the final budget.
An IR illuminated camera will provide you some facial details and can allow viewing of license plates, but this adds a piece of equipment (mounting, power and maintenance) and is susceptible to weather conditions like rain, snow and fog. A thermal camera will cost you a lot more and won’t be able to provide you facial or license plate details, but does cope better with weather conditions. Bottom line: take the time to consider how the scene will be covered in nighttime operations.
6. Get An Image
The saying is really true; a picture is worth a thousand words. If at all possible, try to get an image from each proposed camera location, mimicking the intended view. Getting the image at about the same camera height is ideal, but just getting a snapshot at ground level can also be helpful. This is often difficult to achieve given the nature of site visits and other restrictions, but it will provide you an added level of confidence in your design and help retain some of those small details you may have forgotten after being onsite. Images can be used as a great collaboration tool to gain consensus with the end user on the objective of the camera and ensure that the location and view will achieve the cameras’ intended mission.
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· Systems Integration