One important, but often neglected consideration is the trade-off between image resolution and field of view. With any given combination of camera and lens, the native resolution from the camera is spread over the entire field of view of the lens, affecting pixel density and image resolution. The wider the resolution is spread, the lower the pixel density. The images below, taken with the same camera from the same distance away, illustrate this trade-off. The widest field of view allows you to cover the widest area, but does not allow you to see high detail, while the narrowest field of view permits capture of high detail, but at the expense of wide area coverage.

One Size Does Not Fit All

Another important consideration in systems design is tailoring, understanding the specific needs and using the right equipment to meet those needs. Both the California and New Jersey schools recognized the need for different resolution at different locations. And yet equipment selected for the new California school system reflected a “one size fits all approach”. This was a major fault of the system design which caused the return of the lenses. After installation, it was discovered that the school administration had expected not only to be able to cover the wide parking lot, but also zoom in to see license plates and identify faces at a distance. In this situation a combination of lenses, a wide angle lens for coverage, and a narrower one covering entry and exit points with high detail, could have been used in combination to accomplish both tasks.

A more tailored approach to equipment selection might take longer, in terms of research and testing, and may also mean losing volume discounts achieved through buying units in larger quantities. But the annoyance, time, expense, downtime and safety risk of installing, then ripping out the incorrect equipment and re-installing the correct equipment will be saved.

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Case study 1 - New Jersey High School

The school described their problem as a safety issue. They had unacceptable aggressive student physical behavior they did not want to escalate into violence, as well as some limited theft

Case Study 2 – Southern California High School

Similar to the problems outlined in the New Jersey high school, the safety of students and staff was the primary concern for the administration at the California high school.

Use Available Tools

There are many useful tools available to help support systems design and correct equipment selection.

Do I Need a Megapixel Lens?

Pairing the lens performance with the sensor and pixel size is critical.

Do I need a Day/Night Lens?

In the two school case studies, Theia’s SY125 lens was used. The SY125 lens is not a Day/Night or IR corrected. Was the lens selection correct?

Do Your Homework

It is critical to not only research the system equipment, its features and benefits, but it is just as important to understand the needs of your application.