Securing your premises

Posted on 26 Oct 2004 at 11:41

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LIGHTS, CAMERA, ACTION
Unless you have spotlights to light an area, the camera you choose for night-time surveillance must be suitable for very low-light conditions. The Axis 205, an entry-level camera, is an indoor camera that starts working only at a level of 10 Lux, or twilight conditions.

To keep an eye on what people are doing at night, Hindmarch has installed Axis 2420IR cameras. This moves the installation into a different cost category. Whereas an entry-level 205 costs £125, 2420IRs are £942 each. To say these cameras see in the dark is a little misleading. In fact, they see in infrared light, which means you also have to install IR illuminators that are essentially floodlights for infrared-sensitive devices such as the 2420IR. These cost £300 each, which makes night-time surveillance expensive.

One of the interesting things Hindmarch discovered about infrared cameras is that their focus has to be set up at night. If you set the focus in daylight it becomes blurred when it switches to infrared. This is due to the different wavelengths of infrared and visible light, which affects the strength of the camera's lens. This situation makes summer installations particularly unpopular with Howe, as he has to do a lot of midnight tweaking.

WARNING
One of the unexpected implications of the Data Protection Act is that you have to warn people if you film them in a public place, although the same doesn't apply if you're monitoring your own house. This is one of the reasons you see CCTV notices on garage forecourts.

Another reason for such warnings could be to act as a deterrent. However, it did not work for Hindmarch: people continued to break into the shop and steal petrol after the new digital surveillance system was installed. The difference is that now the evidence is good enough to use for prosecution.

At first glance, the digital footage of a crime doesn't look that much different to analogue footage, as it's still a little furry and indistinct. But that's just because the standard screen image is zoomed out. With a digital recording you can zoom in a great deal. The picture is so clear there can be no mistaking a car's number plate.

HOME MOVIES
If evidence for a prosecution is needed, Hindmarch's system is equipped with an inkjet printer and CD/DVD writer. The printer is used for producing still images, and the CD/DVD writer is used to create video sequences.

Milestone's XProtect software makes it quite easy to cut a particular sequence and export it to an .avi file. Unlike tape-based analogue systems, there's no need to wind backwards and forwards until you find a robbery. If it happened in the day you can skip straight to a particular time. If the shop was closed you wouldn't know what time it happened, but the software adds a flag every time the motion detection system sensed something happening, so it's easy to locate the correct footage.

Despite the simplicity of the system, Howe creates the video CDs and still pictures for Hindmarch. It may look easy to us - especially as CD authoring is a part of Windows XP - but it's something the staff don't want to have to learn.

This means that if the case ever came to court Howe would have to testify to the video's integrity, but to date this is only a theoretical inconvenience. Criminals have always confessed when presented in their starring roles. During a spate of nine thefts in as many weeks, five were resolved in this way.

SECURITY HOLES
Sharp though it may be, digital video surveillance doesn't solve all Hindmarch's problems. Some criminals disguise themselves with hoods or masks and it's difficult to see a way around this - even if they missed the warning notices they couldn't help but see the cameras. And Axis doesn't sell covert cameras.