DORI Explained
At Active Online we work with our customers to assist them in choosing the best cameras and CCTV systems for their project. One of the best methods for guaging how well a CCTV camera will perform in a particular location is DORI.
DORI stands for Detect Observe Recognise Identify and defines the distance for each for a particular camera. Essentially it defines the distance from the camera (straight line from the camera to the target) where you will detect a person, observe a person, recognise a person, or identify a person.
Technically DORI is defined as a “general proximity” of distance based on sensor specification and lab test result according to EN 62676-4 which defines the criteria for Detect, Observe, Recognize and Identify respectively.
What is the DORI criteria for each distance?
The DORI criteria is based on the number of pixels on the target (person) with a higher density of pixels as the criteria increases. For example, a camera sensor is made of a small dots or pixels and the number of pixels is the camera resolution. A 2MP camera has 2 million pixels and usually will be 1920 across and 1080 lines down. An 8MP camera will have 4 times as many pixels and therefore higher resolution.
The requirements for each of the distances is as follows:
The camera is then specified with a DORI distance for each. This is an example for an 8MP camera – VSIPP-8DIRD-I
What the table above tells us is that if you want to identify a visitor or intruder (for police identification) the camera should be no more than 9 meters from where the person will be e.g. an entry gate or doorway or a shed door or shipping container etc.
If you don’t have published DORI for your particular camera you can calculate DORI based on the horizontal resolution (1920 in 2MP example) and the field of view of the camera in degrees. Basically this will allow you to calculate the number of pixels (horizontal) at a given distance based on how wide the view is of the camera. The further you travel outwards the more spread out the pixels will be based on a 1 meter area.
We have a DORI calculator that is free to use on our site and you can access it here: Free DORI Calculator by Active Online
If you would like to know more about choosing CCTV please visit this post: Choosing the right CCTV camera for your application.