How to Use DORI Standards to Determine the Best Viewing Range for Omada Camera Focal Lengths

Contents

Introduction

DORI Standards Explained

Detection

Observation

Recognition

Identification

Key Factors Affecting DORI

Focal Length

Resolution

Other Influences

Best Viewing Ranges for Different Focal Lengths

Reference Table: Focal Length vs DORI Distance

Scenario #1: Wide Area Monitoring (e.g., Parking Lots)

Scenario #2: Entrance/Exit Facial Recognition

Selection and Application Guidance

Conclusion

Introduction

DORI, standing for Detection, Observation, Recognition, and Identification, is a reference standard tailored for cameras, based on the IEC EN62676-4:2015 international standard, to assess their visual range. This measurement method is typically expressed in PPM (Pixels per Meter), defining the count of pixels within a one-meter width at a designated distance from the camera. By employing these PPM values, cameras can be objectively evaluated based on their sensor/lens combination, enabling an unbiased comparison of each camera's long-distance magnification capability and verifying its ability to meet customer performance requirements.

DORI Standards Explained

The DORI standard encompasses four distinct levels: Detection, Observation, Recognition, and Identification. Each level is defined by a specific PPM value and is intended for different use cases.

Detection

The Detection level is set at 25 PPM, allowing for reliable and straightforward determination of the presence of a person or vehicle, though few details will be discernible.

Observation

The Observation level, set at 62 PPM, offers distinctive details of an individual, such as distinctive clothing or unique physical characteristics. This level also provides a broader perspective of the activities surrounding an incident, providing context and assisting in comprehensive incident analysis.

Recognition

The Recognition level, established at 125 PPM, aims to ascertain, with a high degree of certainty, whether an individual appearing in the footage is identical to someone previously observed.

Identification

The Identification criterion, defined at a standard of 250 PPM, enables the unequivocal identification of an individual. This level of clarity is so precise that it allows for the confirmation of a person's identity beyond any reasonable doubt, making it especially useful in high-security scenarios and investigations.

Key Factors Affecting DORI

The effectiveness of DORI is influenced by several technical factors, primarily focal length and resolution.

Focal Length

At the same level, longer lenses or smaller sensors result in a narrower field of view, while shorter lenses or larger sensors provide a wider view. Thus, a longer focal length allows for a greater distance to be seen, which means that an object of the same 1m size will achieve the same PPM at a greater distance with a camera having a longer focal length compared to a shorter one. Therefore, for a given DORI effect, a long-focal-length camera can see farther, but at the same time, its field of view is more constricted.

Resolution

Additionally, another key factor influencing the performance of long-distance cameras is sensor resolution, which determines the level of detail captured within the camera's field of view. For instance, a 2MP camera and an 8MP camera have a resolution difference of fourfold. This means that, at the same approximate distance of 1 meter, the 8MP camera, with four times as many pixels as the 2MP one, can depict the scene with greater clarity. Similarly, at the same PPM value, the 8MP camera can observe from a greater distance.

Other Influences

Other factors such as lens quality, lighting conditions, and sensor sensitivity can also impact the final image quality and DORI performance, though focal length and resolution remain the most significant.

Best Viewing Ranges for Different Focal Lengths

Understanding the relationship between focal length, resolution, and DORI levels allows you to select the best camera model for your specific surveillance scenario.

Reference Table: Focal Length vs DORI Distance

Below is the DORI List for different Omada cameras. You can refer to this table to filter and select the right camera model at first.

Note:

Each value represents the maximum distance (in meters) at which the camera can achieve the corresponding DORI level with the given resolution and focal length.

Scenario #1: Wide Area Monitoring (e.g., Parking Lots)

When the surveillance area is expansive and only human or vehicle shapes need to be captured from a distance, the Observation level is suitable for selecting the appropriate Camera model. Choose a camera and focal length that provide the required coverage and DORI level for your scene.

Scenario #2: Entrance/Exit Facial Recognition

For scenarios such as facial surveillance, where clear images of faces are required, it's ideal to select the appropriate camera based on the Identification level. Similarly, in settings like parking lots where clear license plate information is needed, choosing a camera at the Identification level is similarly advisable.

Selection and Application Guidance

• First, establish the required DORI image quality based on the type and size of your surveillance scene.
• Decide whether detection, observation, recognition, or identification is needed, and refer to the DORI levels and table to select the appropriate focal length and resolution.
• If additional functionalities are required, consider these specific needs and increase the DORI level of the camera as necessary.
• Choose the suitable focal length and model according to your usage preferences and the required field of view for your surveillance area.

Conclusion

DORI standards provide a clear, quantifiable way to compare camera performance for various surveillance needs. By understanding the key factors such as focal length and resolution, and consulting DORI tables, you can select the best camera model and configuration for any scenario—ensuring effective and reliable monitoring.

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