Detection, Observation, Recognition, Identification: How To Find the Best CCTV Cameras Using the DORI Standard.

Choosing the right CCTV camera can feel like navigating a maze of nonsense. You see specs like resolution, focal length, and lux ratings, but what do these numbers mean in terms of what you'll actually see on your screen? How do you compare the real-world performance of two cameras when the key features listed don't seem to offer a clear comparison of image quality at a distance? It's a common struggle for people like us simply looking for a security solution that delivers the clarity we need. 

Thankfully, there's a standardised tool that cuts through this confusion and provide a clear picture of a camera's capabilities: the DORI standard. DORI stands for Detection, Observation, Recognition, and Identification. It's a global framework for evaluating how effectively a camera can capture usable images at varying distances, yet nowhere near enough people have heard of it. DORI is different because it sets realistic expectations and which you can use to select cameras that precisely match your security objectives, ensuring you don't overspend on unnecessary features or end up with footage that isn't fit for purpose. 

In this article, we'll break down the DORI standard in simple terms. We'll explain each of the four DORI levels and the specific metrics behind them, show you how you can leverage this knowledge to your advantage when selecting CCTV cameras, and guide you on where to find a camera's specific DORI performance numbers. By the end, you'll have a clear understanding of DORI and how to use it to make informed decisions for your security system.  

At its core, the DORI standard is a practical way to understand what you can actually see and do with the video footage from a CCTV camera at different distances. It's a standardised system that provides a common language for describing camera performance in terms of image usability for security purposes. 

Think of it as a way to set clear expectations. Instead of a manufacturer just saying a camera has a high resolution, DORI tells you, "With this camera, you can expect to detect a person up to X meters away, observe their characteristics up to Y meters, and potentially identify them up to Z meters." This is incredibly valuable in the real world because the purpose of your security camera dictates the level of detail you need. Monitoring a large, less critical area requires less detail than, say, needing to identify everyone entering a sensitive building. 

The key metric behind DORI is Pixels Per Meter (px/m or PPM). Imagine drawing a one-meter line across your camera's field of view at a specific distance. The px/m value tells you how many pixels from the camera's sensor are spread across that line. The more pixels packed into that meter, the higher the pixel density, and the more detail you can capture.  

The DORI standard is broken down into four distinct levels of image usability, each requiring a specific pixel density (px/m) to be reliably achieved. Understanding these levels is key to knowing what to expect from your camera footage. 

Here’s a breakdown of each level: 

1. Detection 

px/m Requirement: 25 px/m 

What You Can Achieve: At the Detection level, you can reliably see the presence of a person. You'll know someone is there, but you won't be able to make out significant details. Think of it as seeing a shape or outline in the distance. 

Typical Use Cases: This level is useful for monitoring large, open areas where you primarily need to know if there's any activity, such as a fence line or a car park, triggering motion alerts for instance. 

2. Observation 

px/m Requirement: 63 px/m 

What You Can Achieve: Moving up to the Observation level, you can identify characteristics of a person like colour and kinds of clothing. You gain a better understanding of the scene and general activity. 

Typical Use Cases: This level is suitable for monitoring areas where you need more context than just presence, like general walkways, building entrances (where detailed identification isn't the primary goal from a distance), or monitoring traffic flow. 

3. Recognition 

px/m Requirement: 125 px/m 

What You Can Achieve: The Recognition level allows you to recognise a familiar individual or the make and model of a vehicle with a high degree of certainty. If you know the person, you're likely to be able to tell who they are at this level. You might also be able to read larger text or logos. 

Typical Use Cases: This is often desired for monitoring semi-public areas where you might need to identify people you know, such as employees or regular visitors, or for monitoring areas where vehicle types are important. 

4. Identification

px/m Requirement: 250 px/m 

What You Can Achieve: This is the highest DORI level, enabling you to identify an unfamiliar individual beyond a reasonable doubt. At this pixel density, you can expect to capture facial features clearly enough for positive identification or reliably read license plates. 

Typical Use Cases: The Identification level is critical for high-security areas, such as building entry and exit points, sensitive storage areas, or anywhere that requires positive identification for security or investigative purposes. 

Now that you understand the different DORI levels, how can you use this information to select the best cameras for your needs? For a given DORI level, a camera that can achieve that level at a greater distance is, generally speaking, a more powerful camera in terms of its ability to capture usable detail from afar. If Camera A can achieve Recognition at 20 meters, and Camera B can achieve Recognition at 30 meters (assuming all other relevant factors like field of view are suitable), Camera B offers better performance at range for recognising individuals. 

The real power of DORI lies in matching your needs with a camera's stated capabilities. Walk around your property and identify the key areas you need to monitor. For each area, ask yourself: 

What do I need to see here? Do I just need to know if someone is there? Do I need to see what they are wearing? Do I need to recognise them if I know them? Or do I need to be able to identify a stranger? 

What is the maximum distance from the camera to the area I need to monitor at that level? 

Once you've defined the required DORI level and the maximum distance for each critical area, you can then find models that meet those requirements. 

Using DORI helps you avoid common pitfalls when purchasing CCTV cameras. Without understanding DORI, you might inadvertently over-spec your cameras and waste money. For instance, if your primary goal is simply to detect movement across a long perimeter, purchasing expensive cameras loaded with features designed for short-range identification or intruder deterrence would be unnecessary. A camera with strong Detection distances, but perhaps fewer features and functionality, would be more cost-effective and still meet your needs. 

On the flip side, you could easily under-spec your system, leaving huge gaps in your security. If you need to reliably identify anyone entering through your front gate, and that gate is 10 meters from the camera, choosing a camera with an Identification range of only 5 meters simply won't achieve your goal. The footage at 10 meters, while perhaps offering Recognition or Observation, won't provide the necessary detail for positive identification. DORI helps you see these limitations upfront. 

By using DORI, you can select cameras that provide the right level of detail at the right distance, ensuring your security system is effective and your budget is spent wisely. It allows you to build a system where, for example, cameras covering large areas focus on Detection and Observation, while cameras covering your front door prioritise Identification based on the distance you need. 

So you've identified the DORI levels and distances you need for different areas of your property. The next step is to find cameras that actually meet those requirements. Fortunately, manufacturers are increasingly providing DORI specifications to help you make informed decisions.  

The number one resource for finding a camera's specific DORI numbers is the manufacturer's official datasheet or spec sheet. These documents, usually available for download from the manufacturer's website or website you're purchasing the camera from, contain detailed technical information about the camera, including its DORI performance. Look for a section labelled "DORI" or something similar, which will list the maximum distances. 

If the values aren’t available on either of these options, the next recommended step is to contact the manufacturer for accurate numbers. The other options include using an online DORI calculator. An online calculator only gives you an estimate so you need to take it with a pinch of salt. To use this calculator you need 2 pieces of information found in the specification sheet, the horizontal pixels of the camera (3840 pixels for 4K, found in the resolution section) and the horizontal angle of the field of view (101.6 as shown in the spec sheet above). As an example we will use the camera from the spec sheet screenshot above. Here are the differences in the results: 

This over estimation could mean the difference between being able to identify someone at the front of your house or not, a costly mistake if you have to buy additional cameras. 

Choosing the right CCTV camera doesn't have to be a shot in the dark. By understanding the DORI standard – Detection, Observation, Recognition, and Identification – you gain the ability to evaluate camera performance in a way that directly relates to your circumstances. 

DORI provides clear, standardised levels of what you can expect to see at different distances, measured in Pixels Per Meter. By determining what level of detail you need in specific areas of your property – whether it's simply detecting motion or achieving clear identification – you can use a camera's stated DORI distances to make comparisons. 

This approach allows you to select cameras that are fit for purpose, preventing the frustration of under-specced systems that fail to capture necessary detail, and helping you avoid overspending on capabilities you don't need for certain locations. 

Ultimately, understanding DORI puts you in the driver's seat when designing or upgrading your security system. It ensures you invest in cameras that provide the right level of visual information precisely where you need it most, leading to a more effective and cost-efficient surveillance solution.