Mega pixel Surveillance Technology - Part 1

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Video Surveillance Goals

Let's discuss why an end user would even consider mega pixel? This is the most important question because in some instances mega pixel cameras may not be appropriate. Before you look at any camera or NVR/DVR combination you have to initially define the goals for your video system. For simplicity, we narrow the security goals down to three categories:

1. General Surveillance:

These are applications; often live viewing, where you don't need detail on recorded video. For instance, you may be watching a road and looking for traffic jams but do not need to read license plates. Or you may be looking to see what a crowd is doing but do not need to recognize faces. You may simply want to detect when someone is in a restricted area so you can respond immediately.

2. Forensic:

These are applications where you need to see, record, and recognize images like license plates and faces, so you can go back "after the fact" and determine exactly what happened.

3. High Detail:

Applications where you need to read a license plate but also read the model of the car. In retail or banking context, you need to clearly see the customer's and employee's faces as well as identify the currency in their hands.

By assigning a category to your application you are, in fact, defining the resolution requirements. With older surveillance technology, resolution was defined by its TVL (television lines, a.k.a. total video lines). Over the last few years the market has evolved to defining resolution by the total number of pixels. This is more objective when comparing products that have different resolutions. So, when an image is 640 x 480, that is actually 640 (horizontal or columns) pixels x 480 (vertical or rows) pixels, for a total of 307,200 pixels, or approximately 0.31 of a mega pixel (million pixels).

But resolution can only be defined by pixel if you determine how wide an area those pixels will be covering. How do we determine that? It's all about pixels-per-foot.

Coverage Defined by Pixels-per-foot

For general surveillance applications, you need approximately 20 pixels per foot. Forensic applications require about 40 pixels per foot, and high detail applications demand at least 80 pixels per foot.

Once you have defined the type of application you have, and you know how wide an area you have to cover, you can figure out if mega pixel is right for you. An example will make this much clearer. Let's say you want to cover a parking lot with forensic detail and the lot is 100 ft. wide.

For simplicity, we will only discuss here the width (horizontal field of view). For a true analysis, you need to factor in the width and depth.

100 ft. x 40 pixels/ft. = 4,000 pixels, which is what you will need to cover that 100 foot area and recognize license plates and facial detail. Once you have this, the rest is easy.

The next step is to determine what resolution cameras you want to use. You determine this by dividing the number of pixels you need to cover the area (in this example, we've determined that count to be 4,000 pixels) by the number of horizontal (columns) of pixels provided by your camera.

If you use 320H x 240V resolution cameras (0.07 mpix) you perform the computation by dividing 4,000 by 320. The result is 12.5, so let's put that at 13 cameras.

At 640 x 480, (0.31 mpix) you divide 4,000 by 640, and you come up with 6.25 cameras, so we round up to 7 cameras to make sure we've covered the scene fully.

If you're working with 1280 x 1024 (1.3 mpix) cameras, the scene would call for 3.25 cameras; four cameras will surely cover the area.

As you move up the resolution ladder, you can compare cameras that create images equal to 2048 x 1536 (3 mpix). Using those resolutions, two properly positioned cameras will do the job.

The Realities of Pricing

Let's compare a non-mega pixel installation for the parking lot with the highest level mega pixel cameras in this example.
A high quality camera made by an established manufacturer that delivers a 640 x 480 image has an RRP of about $770.

A high quality camera made by an established manufacturer that can deliver a 2048 x 1536 image has an RRP of about $2000.

A high-quality outdoor heater/blower housing has an RRP of $225 and 30 meters of Cat 5 cable can be purchased for $20
(coax would be more expensive, but let's assume that we're comparing IP cameras that connect over Cat 5 cabling).

Let's include $100/unit of labor to install a camera and do the math:


640 x 480 camera $770 x 7 (required to cover scene) $5390.00
Housing $225 x 7 $1575.00
Cable $20 x 7 $140.00
Labor $100 x 7 $700.00
Total $7805.00

2048 x 1536 camera $2000 x 2 (required to cover scene) $4000.00
Housing $225 x 2 $450.00
Cable $20 x 2 $40.00
Labor $100 x 2 $200.00
Total $4690.00

Obviously, this is a rather simple model; however, it demonstrates that mega pixel systems prove to be less costly if you have a wide area to cover(where forensic detail is required).