Some thoughts on camera placement
In this article I will discuss some of the aspects that are important when considering the placement of cameras in your security system.
You’ll notice that I used the term “security system”. It is important that cameras are placed in a manner so that they complement each other. Each camera should be targeting a particular area in such a way that the likelihood of capturing an event is maximised. Too often, sometimes in an effort to cut cost, business owners will purchase one or two cameras and set them so that they each capture a wide area, the field of view. This approach frequently leads to disappointment when the recorded video lacks sufficient detail to clarify a sequence of events or clearly identify an offender.
Using an example, if a thief was to enter your premises, you would want a wider shot to observe their general behaviour and movements but, at some point, you want a camera positioned in a location that would capture sufficient detail to enable the culprit to be identified.
There are several other practical issues to be addressed when deciding where to place cameras in a video security system.
First off, let’s talk about the actual physical location.
Two of the most common places for mounting security cameras are the entrance and exit to the premises. A camera mounted too high will not capture sufficient facial detail of anyone coming in to the building. An image of the top of someone’s head will not be very beneficial to police. Similarly, a camera mounted too low is susceptible to interference or vandalism. There is always a sweet spot where the camera mounting is sufficiently out of arms reach yet still able to capture recognisable features.
While on the issue of height placement, it is important to remember that the camera may require periodic maintenance. Something as simple as dust accumulation on the lens can render a camera useless. I have experienced several instances where spider web has obstructed the field of vision. It’s important to be able to reach the camera so that it can be cleaned when necessary. This is especially important when cameras are mounted outdoors.
When positioning a camera to focus on, say a car park entry gate, rather than determining placement from the intended mounting position, work out where you think the camera will go first. Then, form the target area, look back at where you want the camera mounted and make sure that you can clearly see the spot. It’s surprising how often a target viewing area looks fine from the camera location but, when you look back the other way, obstructing objects become obvious.
A camera should not be positioned in such a way that someone can avoid detection by coming up behind the camera and disabling it. Either a camera should be mounted so that it is only approachable head on, within the field of view, or there is another camera which will capture the area and activity behind the first camera. This reinforces the concept of a security system.
Lighting is another critical factor when determining camera placement. Cameras need light. That’s how they form an image on the sensor in the same way that your eye captures light hitting your retina.
However, lighting is tricky and there are lots of factors to consider, particularly when you need to capture images both day and night.
Most important is changes in light throughout the day. It is important to consider the movement of the sun where the camera is located. Cameras facing east and west have a particular challenge with direct sunlight hitting the lens. This will cause an image to be washed out and will quickly damage the light sensor.
Backlighting, where there is a light source behind the target, is also a problem and causes the target to become silhouetted, thereby destroying image detail. It is always desirable to locate a camera where it will not encounter a direct light source at any time.
Many cameras are equipped with infra red LEDs. These will illuminate the field of view at night, even in complete darkness. IR illumination will depend upon the number and rating of the LEDs and this will, in turn, determine how far into the FOV the camera can see and how much detail it will capture. Supplemental infra red can be added with a separate IR lamp or spotlight if necessary.
Infra red is an area of the light spectrum which is invisible to the human eye. To an IR camera, however, it provides a light source. As such, an important consideration when using IR cameras is not to let the IR from one camera shine into the lens of another as this will blind both cameras. Similarly, cameras should not be placed such that there is a direct light in the field of view at night or that the camera is mounted directly below or in the path of internal lighting. All of these scenarios will impair the ability of the camera as it would if you were to try and discern activity behind a spotlight shining in your eyes.
A final lighting issue involves shadows and glare. Over the course of the day, shows will move and may obstruct detail. Glass creates reflection and glare and so cameras should not be focused on areas beyond a glass window or wall.
A final note on camera placement concerns motion detection.
It is now common to configure cameras as recording units to identify and record a period of time around the detection of a motion event. This often makes it easy to quickly identify activity in the field of view. While it is generally inescapable to have events such as domestic pets triggering motion detection, cameras should be positioned to try and avoid incidental detection. This can happen when the wind blows and a plant leaf or branch in the FoV moves. If this happens too frequently, motion alerts will be numerous and most will be of no use.
This has been a fairly long article but the purpose was to demonstrate that there are many factors involved in determining good camera placement to maximise the return on a video system investment.
If you would like further advice or information, please contact Bluefly to arrange a consultation with one of our friendly and helpful consultants.