How to build a surveillance camera system

STEP 1: Determine your cameras’ raison d’être.

From this you’ll be able to decide just about everything else. In my organization, we concluded that surveillance was primarily for forensic use, which meant it had to:

• Let us rapidly review detailed footage so that after incidents (accident, crime, terrorism, overcrowding and so on), we could back everyone up from the event to the edge of our

  property to see who they talked to, what car they drove, where they parked, what bus or taxi they got

  out of, what condition the facility was in at the time (icy sidewalk, wet floor, tools in the area and so

  on).

• Be on demand, because we can’t watch the cameras all the time. We wanted to

  be able to call up the camera with the best coverage to monitor situations if and when we were called

  by someone with an ­incident report.

• Allow for targeted “smart” cameras for high-risk areas. We wanted the cameras

  to be able to alarm us when something began to happen.

STEP 2: Take an inventory.

If you have cameras already, survey what departments own them, what they are for, how they are

monitored and what format they use, then decide if any of these cameras can be folded into your new

system.

STEP 3: Get smart on camera technologies.

Determine the effect of new technologies on operations, training, maintenance and staffing. Determine

how clear you need the picture to be (as opposed to how clear you want it to be). This will have an

impact on costs. Here are some of your choices:

• Frame rate. The more frames per second (fps) you choose, the more

  network capacity each camera will require and the more data storage you’ll need. A Fortune 50

  company I contacted is using 3 fps to watch cash registers. Its studies showed that no human can trick

  the camera in a third of a second. We are using 10 fps because our analytics software requires a

  minimum of 7 fps and we can use only multiples of five. Note here that if you are expecting to catch a

  baseball in flight you’ll want a high frame rate, possibly 30 fps or full motion video, but that’s going to

  be more expensive to operate.

• Resolution. Similar to frame rate, but this is not a motion issue; rather, it’s a

  clarity issue. The clearer your picture, the more pixels it will have, the larger the file will be and the

  more bandwidth it will consume. We determined that Quarter CIF (Common Intermediate Format,

  352×288, which is the default frame rate for DVR systems and is one-quarter as clear as your TV at

  home) is perfectly OK to provide an image to the police that they can use to find and apprehend a

  suspect. If you expect to get mug shot quality out of your video surveillance program then you’ll want

  full CIF (TV quality), but you’ll pay for it in terms of bandwidth and storage.

• Compression. There are several standard commercial compression algorithms,

  but the most common, for all the right reasons, is MPEG-4. We went with that because it is economical

  and has all the clarity and ease of use we need. You can add a commercial compression package to

  your MPEG-4 to further reduce your storage needs.

• Storage duration. Thirty days of storage is the unofficial national standard.

  This gives most of us enough time, without overdoing it, to learn of an incident before the data is lost.

  When you get an event of interest, you should plan on dropping that file onto a DVD and storing it

  indefinitelyor at least until all criminal and civil proceedings are concluded, including appeals.

  You can also send events of interest to a separate server for indefinite storage.

• Storage size. I did the math: A single digital camera running 24 hours at just 5

  fps, using MPEG-4 at Quarter CIF resolution, creates 11GB of information. That’s 330 gigs per month

  for just one camera! A 500-camera system, not at all uncommon for corporate buildings and campuses,

  will generate 165 terabytes every month. So it’s easy to see why keeping pedestrian images beyond 30

  days is economically foolhardy. And remember, this is with cameras running on spare frame rates and

  resolutions. Full motion video (30 fps) will create 990 terabytes, almost a petabyte, of data. If you also

  go to full CIF, multiply that by four, and you’re talking a few petabytes a month! Stay on top of the

  contractors and consultants so that they stick to the original engineering discussions, or they could

  easily overdo your system. Mission creep can be expensive. And remember, it’s not just storage but

  also bandwidth you have to consider. How are you going to move 5,500GB of digital video through your

  network every month?

• Digital vs. analog. At some point you’ll want to convert your images to digital

  to take advantage of its easier storage and better retrieve and search capabilities. But analog images

  can travel farther from the camera, so cable runs will impact your choices. A consultant can advise you

  on the best route to go.

• Pan Tilt Zoom (PTZ). There are two ways to do this. The old-fashioned way,

  which still works really well, is to physically move the camera and change its focus whenever you want

  to get a close-up. Dome cameras have a dark bubble over the camera to mask where it is pointed at

  any given time. Make sure each PTZ has a default “park” position that gives you an optimal view and

  focal length. It is easy to forget to do this and leave a PTZ where it was last focused; this will likely not

  give you the best coverage when nothing special is happening. The other (more costly) way to do PTZ is

  digitally, within the image itself. This will require megapixel images. Zooming in on, say, a license

  plate, will fuzz out the image illegibly if you don’t start with sufficient pixel density in your camera

  platform.

Step 4: Wrestle a few more issues to the ground.

• Monitoring. This is a contentious issue. The public may expect that

  cameras are monitored all the time, but it’s neither practical nor possible. The best you can do is put

  your high-­priority camera images up in your command center for occasional viewing. Even better:

  Use analytics software to pinpoint an event of interest and call it up with an audible alarm.

• Decoys. It may be tempting to use dummy camera domes to suggest you have

  surveillance, this will give your public a false sense of security. Most competent programs avoid their

  use, except in specific circumstances and then only in concert with live cameras.

• Staffing. It’s unrealistic to expect to be given additional staff to monitor a new

  suite of cameras, and it’s equally unrealistic to expect to get different people than the ones you have

  now. For these reasons, you will want to choose a system that has a simple GUI (graphical user

  interface), provides out-of-service alarms for cameras and encoders, is low-maintenance and has high

  mean times between failures.

• Privacy. Make absolutely certain you supervise the troops who access cameras

  and images. If you don’t, inevitably, your cameras will be diverted to personal, voyeuristic use, which

  can have serious, negative impacts on your company image once the antics are publicizedand

  they will be.

• Signage. Get advice from your legal counsel regarding signs to announce video

  surveillance on your property.

• Policies and procedures. If your cameras can view geography off your property,

  consult with your software provider to mask out these areas. This is especially important if you have

  line of sight to residential properties. Supervision and the application of swift discipline are very

  important to avoid inappropriate use.

• Training. The more complex your system, the more training the staff will need.

  This takes good time management because unless you have a full shift to go on training rotation, you

  will be doing training on overtime.

• Maintenance. Include in your maintenance contract a service-level agreement

  that guarantees your high-priority cameras are fixed promptly. Be sure it requires an adequate stock of

  onsite replacement cameras and network encoders and other peripheral devices so that the most

  important cameras can be restored to service quickly. Your system should open a trouble ticket

  immediately upon device failure, and you will want to review the system’s performance monthly to

  ensure you are up to speed on how reliable it is and which parts are giving you the most trouble.

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This article was written by a CSO who requested anonymity to present this level of detail.

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