A guide to enhancing video surveillance in public areas and retail environments.
Why you should read this
Many businesses and councils have CCTV installed but unfortunately of all the video surveillance cameras installed it is estimated that only 40% are working correctly. That’s not saying they don’t work but rather that they don’t provide the image quality that matches the application.
For example a petrol station camera that cannot read the number plates at the pump or identify a person at the counter.
For those who would like to understand how to get the most from their CCTV system, read on…
For those who would like to understand how to get the most from their CCTV system, we will be covering a range of topics including camera placement for different applications, recording resolutions and rates, storage time and lighting.
The real difference between a having a few video camera installed and a professional CCTV system does not always come down to the dollars but rather an understanding of what you want to achieve and how to go about it.
The general public’s perception of CCTV
TV shows and movies like CSI may be the reason people have unrealistic expectations from what a video surveillance system can achieve. It has not been uncommon in my career to be asked why I can’t enhance a face or a vehicles number plate from a really crappy recording and when I try to explain that the camera was not setup in a way to achieve what they are asking I get a look as if I’m joking.
Having been working in the security industry since 1988, I have seen some amazing advances in what can be achieved with a CCTV camera but the public’s expectations still far exceed the reality of the real world. In addition to the TV shows putting misleading ideas into peoples heads, the manufacturers also like to make their products sound like they can give amazing results in any situation.
Yes we can auto track a person with a PTZ (Pan Tilt Zoom) camera as well as seeing in almost total darkness but for every great feature, there are always other factors that need to be considered before choosing a camera and its location.
Common Misperceptions
1. The same camera can watch a wide area and ID a person
2. Mega pixel cameras can replace several standard cameras
3. The recorded image can be zoomed in
4. All recorders are the same
5. Cameras can see in total darkness
6. A PTZ camera is better than a fixed camera
Let’s take a quick look at each of these and follow up with more detail later on.
The same camera can watch a wide area and ID a person
A common practice is to install a camera that gives a wide view of around 60° or greater as this means one or two cameras can cover a large area, which in turn reduces the installation cost.
The problem here is unless the camera has a very high number of Mega Pixels (MP) a person even 2 metres away will not be able to be identified due to a low pixel density. Refer to page 2 for more detail about this. The best practice is to have a wide angle camera combined with a tighter angle camera at a choke point such as the entry door, a corridor or the counter. This will allow you to identify the person and track their movement, which is what you need for evidence, which is covered in detail on page 3
Mega pixel cameras can replace several standard cameras
On a purely technical basis this is true. A 1.3MP camera is the equivalent of 3-4 standard analogue CCTV cameras but depending on the scene you may not gain this benefit. There is always an improvement in image quality from a properly setup megapixel camera but unless they are in a large open are, in many situations 3 standard cameras will give better coverage as they can be positioned to give different scenes. Most shops should have a camera at the entry door, the counter and an overview of the isles for best results.
Having said that, I do recommend that you use cameras of at least 720p HD (1.3MP) resolution as you will always get crisper images but don’t think that by putting in a 5MP camera will give you the same result as 3x 1.3MP cameras. It wont!
The recorded image can be zoomed in
Nearly everyone expects that with the right software, an image can be zoomed in and cleaned up to get the fine detail and in some cases it can but this depends on the camera resolution as mentioned above as well as the recorders compression. If an image is compressed heavily to give more recording time, the image quality is reduced and so is the ability to zoom in on fine detail.
All recorders are the same
The Digital Video Recorder (DVR) can record several cameras at the same time but the image quality that they record are will vary from brand to brand due to how they implement their video compression. This is often impossible to compare based on a sales brochure so asking your sales person for a test recording is recommended but unless you know what to look for, may not highlight the differences. The best option is to use the advice of an experienced installation company.
Cameras can see in total darkness
This is a true statement but it does not mean that the image will be useable. Many cameras include an array of infra red LED lights (IR) but without any method of dispersing the light evenly. The result is a bright spot or hot spot on the person as they walk through the scene, making the image flare out in a similar way to trying to see while having a spot light shone in your face.
Cameras need consistent light with as few as possible excessively bright spots.
A PTZ camera is better than a fixed camera
This is only true if you have an operator controlling the cameras live so they can zoom in and out of points of interest. If that is not an option, you will get better value installing 3-4 cameras, each with a different view such as 2 with 70° wide angles and the other 1 or 2 with a tighter view that might give a recognition image further into the scene.
Still reading?
Great because you are clearly serious about your CCTV design working.
If you leave a comment below, we will answer any questions you have on improving your CCTV system dersign.
