How many megapixels do I need for business security cameras?

Many of the most common questions we get from business buyers and decision makers of security cameras are related to whether their cameras are good enough or not or how good they need to be. 

• “How many megapixels should we buy?”

• “Is HD enough?” 

• “How does this compare to 1080p?” 

For commercial buyers, there isn’t an easy one-size-fits-all answer. Commercial security systems cover a much wider array of facilities and scenarios than residential systems. We’ve installed cameras in places ranging from cramped entry hallways and claustrophobic liquor closets to thousand-foot-long warehouses and full-length strip mall parking lots. 

Planning the right coverage for each case involved assessing the space, the camera, and the job to be done. To begin with, a site survey is recommended to fully assess the size of the site, along with lighting conditions and any obstructions. Angles and elevations are also observed. 

Stakeholders are consulted on what they need from the cameras. While, at a glance, it may seems like one security camera task is much the same as the next, there are important differences in tasks. Some examples of different scenarios include a remote business owner who just wants to know when people are in the building; a business that is having problems with illegal dumping across the parking lot; a retail store that wants to minimize employee theft; or a warehouse that wants video of safety incidents to review in training. Some of our most challenging projects have involved clients with small, valuable merchandise like jewelry or cell phones that must have forensic-quality video of key storage and display locations. 

Finally, based on site and task, a selection of cameras are then assessed. The most important components of the camera for assessing resolution are its sensor and lens, as well as compatibility with existing systems. Other conditions like exposure to the elements, presence of hostile actors, operational needs for thermal measurement, license plate recognition, or video analytics are also considered. 

It would be easy to simply recommend the highest resolution camera that meets other needs, but of course, higher resolution requires higher costs upfront and higher data storage costs (or lower video retention periods) on an ongoing basis. So we try to avoid overselling just for the sake of extra resolution. 

To make the final decision, we often rely on a well-established framework called DORI.

Not this Dori.

DORI stands for: 

Detection

Observation

Recognition

Identification

Each level means something slightly different and requires higher resolution. An example of how each level might be interpreted for an illegal dumping use case: 

Detection - There is movement by the dumpster. 

Observation - It is a silver vehicle. 

Recognition - It’s a silver Toyota RAV-4…

Identification - … with license plate YYY-1234. 

We can bucket camera tasks into these different levels. As we move from Detection to Identification, the required pixel density (measured in pixels per foot, ppf) increases. At any given distance, it requires more pixels to identify a person or vehicle than it does to simply detect motion. 

Detection - 8 ppf

Observation - 19 ppf

Recognition - 38 ppf

Identification - 76 ppf

How many ppf you get from any given camera is a complex mix of distance, lens, sensor, and lighting. Luckily, there are tools that we can use to help us plan for these factors. 

A DORI map from JVSG.com

The screenshot above shows a handy lens calculator that helps assess DORI zones for a selected camera over a selected range. We can use this tool to help right size the resolution needed for a specific site. Of course, final recommendations will factor in other considerations like environmental factors discussed earlier or range limitations of an onboard infrared light. For clients with forensic-level needs, additional analysis may be needed to scope pixel density needs. 

You can use the tool linked above to get an idea of how your camera setup might work. 

Of course, unless you simply like playing with camera coverage maps, we are here to help with the hard part. Site surveys for commercial clients in our Dallas-Fort Worth service area are always FREE. We will assess your site, scope your coverage needs, and draft a customized site coverage plan with no cost or obligation to you. You can click here to get in touch: