Mar 1, 2001 12:00 PM, CHARLIE R. PIERCE
Over the past 15 years, we have been invaded from every direction by new manufacturers of CCTV equipment. This invasion has followed the trends of the times. Fifteen years ago, you couldn't count the number of new designers and makers of CCD cameras. Twelve years ago, it was multiplexers. Ten years ago we were swamped by the new technology of 24- and 72-hour, high-density recorders. Eight years ago it was mini-domes with chip cameras built in. Four years ago it was auto-domes. Two years ago started the phase of digital recorders, digital management systems, and storage equipment. And today, we have a new group of CCTV mystics promoting their PC-based systems. You can't go near a magazine, a security show, the Internet, or your neighbor's sons or daughters without running into a PC wizard.
The result has been the promotion of interesting and often confusingly inaccurate information ¡ª all in the name of marketing. Examples: 15 years ago, CCD cameras were promoted as being a flat-surface technology and so having no distortion of image as compared to tubes. However, no one pointed out that the lenses used with these flat CCDs were not flat-surface technology and caused most of the image distortion the CCD was supposed to correct. Ten years ago, the first multiplexers were promoted as enabling us to record up to 16 cameras simultaneously on a single VHS tape ¡ª truly a misconception of high-speed switching. Six years or so ago, 24-hour, high-density video recorders were promoted as being able to provide 24 hours of "real time" video information on a single three-hour, VHS tape ¡ neat trick, if it could be done. Today we just say that these units record in "virtual real time." Not quite accurate, but a nice compromise.
If you have looked around lately, you have seen a huge number of companies coming at you with PC-based video systems. Not just PC-based controlling systems with fancy GUI screens, but PC-based everything ¡ª controls, storage, images, transmission, etc. It makes one think he is in the middle of the newest syndrome to hit the CCTV industry ¡ª a syndrome I call "Video Games."
Yes, here we are folks. It started with Pong and has gone straight to security from there. A difference in this latest syndrome is that this time there are many more players, and many of the players are not sporting a security, let alone a video, background. Instead, they are computer programmers and computer experts. What does this mean to you? It means buyer beware! As usual, there are all sorts of myths and promises mixed in with the facts.
I recently read an article with a headline that claimed less than 1 percent of recorded video images are of value to security directors. I had always figured there was a percentage of video that was useful, but had never seen a formula for determining just what percentage. So I read on.
According to the article, a study was done specific to applications in one industry. The first red flag to be raised is that not all security applications are equal. However, the article promoted the results as valid to any type or level of security. I concluded it was a limited study with no bearing outside the industry it addressed. So why is it being used as a selling pitch to other applications? Maybe because the writer doesn't understand the differences among security applications.
Now the math that supports the headline's claim: The writer calculates that each camera presents 2,592,000 frames of video information for recording each 24-hour period. He further states that over a nine-month period, a consistent average of 46,000 pictures or frames are of any value within each five-day period. Working backwards, this represents about 25.55 minutes of useful video each 120 hours. The writer continues that 12,960,000 frames are recorded every five days, so the actual number of useful images represents 0.004 percent or less than 1 percent of the overall information. Frankly, I would have thought it to be less. The writer then goes on to state that there are 8 cameras (average) at each location so the total number of images presented to the multiplexer every day is 2,592,000 ¡Á 8 or 20,736,000. This, of course, is the first point of fog. Yes, we present 20 million pictures to the multiplexer, but we still only record 2.5 million images each day in real time ¡ª quite a bit fewer in time-lapse.
The concept here is correct ¡ª record and store only that information that is of value. However, the idea that every camera's view within any/all application(s) can be limited to two pictures per second shows a lack of experience.
What about the fact that the original 1 percent of valued information was mixed in with the other 99 percent of worthless information. What is the criteria that separates the two formats of information?
How did you record that valuable few seconds of visual information? Did a PC sit back and say, this is of value and this is not? Perhaps you recorded what you felt was necessary and got lucky. Yes, today's systems need to be automated and streamlined as much as possible. However, do not let anyone justify to you their inability to store real-time information as based upon the lack of need. All applications require real-time information from time to time.
(My intent here is to educate, not to slam. This problem is not restricted to a single writer or manufacturer, but is widespread.)
An alarm interface is how security is supposed to be designed. However, what is the criteria of the alarms? With PC-based technology, we are often dealing with systems designed to record limited information while claiming to fulfill security needs. It has been the theme song of most of the manufacturers of PC-based systems over the past three years ¡ª hide the obvious limitations of the system's storage capability while promoting the strong points of organizational wiz-bang magic.
The next point of PC-based systems is that the information is recorded, on a hard drive or disk or whatever, with the time/date stamp, camera number, and even (in some cases) frame number. Consequently, I am able to recall information in a heartbeat, from any PC attached to the system, without having to shut down the entire system and spend hours reviewing video tapes. This is great. However, what are we giving up to gain this sudden and wonderful search capability?
One thing might be resolution ¡ª it's everything when it comes to visual evidence. If your images are of objects and/or persons that are large enough to take up more than 10 percent of the width of the scene, then you probably have enough image that you don't have to worry too much about resolution. However, 640 ¡Á 480 pixel resolution (901 Kbytes) visual images are small and end up needing to be enlarged for distribution and/or printing. The 640 ¡Á 480 pixel resolution (901 Kbytes) is OK provided you do not intend to enlarge the image beyond a 4 ¡Á 3 print. Anything larger than that and your image gets grainy and loses detail quickly. Now, compress that further to 25kbytes to conserve space on your hard drive, and you are in trouble. Compression, in simplest terms, means that we will remove x percentage of pixels until the image can be squeezed into a smaller frame. The new compressed image looks great as a 1-in. by 1-in. picture. However, blow it up, back to your original 4-in. by 3-in. print and you will find that you have lost a whole lot of detail or resolution. Enough in some cases that you cannot identify a person standing in front of a camera.
PC-based systems also, according to various articles, add the time date and other such information to the image to make this image stand-alone evidence in court. OK, so let's look at the evidence. First, the quality of the image is what will make it good evidence ¡ not the time/date stamp. Time/date stamp is good, but not necessarily the key to visual evidence in a courtroom. Second, are you ready to turn your hard drive over to the courts for storage as original evidence? If not, you might want to think about this system. Third, courtroom evidence, from the perspective of video, is more convincing when it includes action versus individual images. Twenty-three-plus years ago, time-lapse video recorders first hit the market hard. Banks all over the country were sold a bill of goods by being told that they could remove their expensive film cameras and replace them with CCTV cameras and time-lapse video recorders. The first problem was that the recorders had one fifth the resolution of the original film cameras. Consequently prints from the video recordings were not of high enough quality to assist the FBI in identifying the bad guys.
Second problem was the amount of time lost by switching from camera to camera. Even in an alarm situation, it was very possible that a holdup could happen and no visual information would be recorded. Finally, the last problem was the storage of videotapes. Most banks were not equipped to handle the storage problems. Consequently, tapes were not properly stored, rotated or processed and information was lost. Additionally, camera images were not clear, focused, and/or close enough to the subject. What does this have to do with PC Systems?
Simple. Yes, these systems have some good stuff to offer and in some cases are good for the whole show. However, for the most part, what you gain is not necessarily worth what you have to give up. If your initial images are not right, a PC-based system, at this point in design, will only add to the problem.
The last word on this entire article is ¡ Buyer beware! Read very carefully between, above, below and through the lines of anything/everything that a manufacturer prints. Their job is to produce and sell equipment. Your job is to purchase it. So purchase wisely and learn to extract the truth from the hype. If nothing else, send the copy in question to a specialist and ask questions.
There is nothing worse than investing money into a great idea that cannot carry the full weight of the burden of evidence. Remember the lesson of the video recorders and film cameras. Use of both technologies in concert allows each to play off the other's strong and weak points.For the Record ABOUT THE AUTHOR
Charlie R. Pierce, president of LRC Electronics, Davenport, Iowa, is a leading authority on CCTV and a regular contributor to Access Control & Security Systems Integration.