It is not complicated to decide what camera resolution is right for you, however it can be confusing if you aren’t familiar with best practices. How to make sure your video surveillance system is capturing the needed detail in a scene, without incorporating high-level megapixel cameras which your customer may not require?
DORI stands for Detection, Observation, Recognition and Identification, which is championed by the British Security Industry Association and Department of Homeland Security to delineate categories of identifiable information.
The detection level allows reliable and easy determination of whether a person or a vehicle is present and requires 10 Pixels Per Foot (PPF).
The observation level provides characteristic details of an individual such as their clothing, while allowing a view of activity which surrounds an incident and requires 20 PPF.
The recognition level determines with a high degree of certainty, whether an individual shown is the same as someone that has been seen before and requires 40 PPF.
The identification level enables the identity of an individual beyond a reasonable doubt and requires 80 PPF.
2. Calculating the Pixel Density
In order to calculate pixel density, you must simply divide the horizontal pixels of the camera resolution by the Field Of View in feet (FOV) of the observed scene. As an example, a 4-megapixel camera with 2,688 horizontal pixels used to cover a loading dock with a 100-foot FOV, pixel density would be approximately 27 PPF.
3. Selecting a Camera
Factors such as the lens, compression and placement of the camera impact the clarity of the image aswell as weather and environmental conditions, which should always be taken into account. You must always make sure to consider the scope of the entire surveillance system before rushing into installing a higher megapixel camera, as sometimes you may only require a high megapixel camera in the entrance to a building in order to help accurately identify a persons face and can therefore use lower megapixel cameras to monitor the activity. This would help you have the confidence that your camera will cover areas which you need to monitor at the level of detail which is required to monitor the location. This could not only help meet your customers viewing requirements but can also ensure that your customers don’t overpay for equipment.
4K vs. 8MP CCTV Cameras
Both 4K and 8MP Cameras are effectively interchargeable. The term 4K has originated in broadcast television in order to refer to 3840 x 2160 resolution at 30 or 60 fps. The total number of pixels of a 4K sensor would be around 8.3MP. 8MP cameras means that any pixel array which equals around 8 million pixels, which doesn’t have to be 3840 x 2160, however most of the times it is. IP security cameras usually have a frame rate of 12 to 20 fps (not 30 to 60 fps) but many security manufacturers call their 8MP cameras 4K, because both of the camera types total pixels are 8 million and the sensor array is 3840 x 2160.