Eric Olson, Vice President of Marketing
When designing a perimeter surveillance system, or even when adding new sensors to an existing system, itís easy to get caught up in the product selection, perimeter layout, camera locations, lens size and image resolution.† Unfortunately, most of this planning overlooks a very important aspect, which impacts at least 50 percent of your surveillance systemís intended purpose, night time operation. †In almost all cases, the limiting factor in all surveillance coverage occurs at night. Before any security sensor is purchased, or added to your existing security system, you need to ensure you are considering operation in no light or low light situations.† †For video surveillance, there are two main choices: a thermal camera or a visible camera with illumination.† Here are six things to consider when making the choice.
We all want world class protection for our facilities, but itís not often we have a budget that supports that goal.† This is a key point when deciding the type of sensor that works the best for your night time surveillance needs.† Although thermal cameras continue to drop in price, in general, a solution utilizing thermal cameras tends to be more expensive.† This is especially true when implementing a surveillance solution which includes cameras with pan-tilt capability.† However, when considering cost as a factor, make sure you include the full cost of visible cameras.† Visible cameras will require some type of illuminant.† That could be a dedicated infrared illuminator, or a series of white light sources, such as street lights, etc.† The cost of this equipment, including installation and power must also be considered when making your comparison.
Itís worth mentioning that before selecting a security sensor, itís always good to first do your homework and define the objectives of your security system. In many cases, having a verified intrusion is the primary objective, however, if your protection scenario demands the collection of specific details about your target Ė license plate, colors, driver information, facial details, then itís important to know that this information is not always available through a thermal sensor.† This requirement may dictate that you ensure proper lighting, and utilize visible cameras to achieve this type of intrusion details.
Although not limited to low light conditions, one must consider desired performance of the surveillance system during various environmental conditions.† All sites experience some type of weather conditions, be that rain, snow, sleet or blowing dust.† Visible cameras can be susceptible to many forms of weather interference, while thermal cameras, tend to be immune, or at least impact to a lesser extent.
Somewhat related to the consideration of cost is pan-tilt-zoom capability.† Cameras with pan-tilt-zoom capability allow an operator to direct the view of the camera to any location, and zoom in to provide greater detail of the target.† For the visible camera, this functionality comes at a very reasonable price.†† The only cost consideration is providing illumination to any area where you may want to steer the camera, or zoom in, during night time operation.
Conversely, thermal cameras suffer a cost disadvantage in this area.† Thermal cameras equipped with pan and tilt mechanisms can be considerably more expensive than their visible camera PTZ counterparts.† Likewise, the ability to zoom dramatically increases the cost of commercially available thermal cameras.
Field of View Considerations
Similar to detection range, night time operations create special considerations for field of view and width of coverage.† Once again, thermal cameras are straight forward, with the sensor size and lens dictating the same field of view in both day and night conditions.†† However, visible cameras are subject to the coverage of the illuminator.† Just like cameras, illuminators have their own field of view.† If the field of view of the illuminator and the camera do not match, it can result in a variety of undesired conditions, such as decreased range or reduced width of field.
Ensuring your surveillance system is designed to operate in no light or low light conditions is paramount to the ultimate safety of your assets and facilities.† Visible cameras with illumination or thermal cameras are both excellent choices which will help you achieve this goal.† However, each sensor has its own characteristics that you must consider before choosing the one that will best fit your needs.† Assessing your security needs against these six considerations will help in the selection of the best sensor for day and night time surveillance.