How this calculator works
The width of the scene at a given distance comes from the horizontal field of view. Pixel density is the camera's horizontal pixel count spread across that width:
Scene width = 2 × distance × tan(FOV ÷ 2)Pixels per metre = horizontal pixels ÷ scene width
The maximum distance for each DORI level is that formula solved for distance, using the thresholds from IEC 62676-4:
| Level | px/m | px/ft | What you can tell |
|---|---|---|---|
| Detect | 25 | 8 | A person is there |
| Observe | 62.5 | 19 | Clothing, activity |
| Recognize | 125 | 38 | Someone you know |
| Identify | 250 | 76 | A stranger, beyond doubt |
Frequently asked questions
What is DORI?
DORI stands for Detect, Observe, Recognize and Identify. It is the set of pixel-density levels defined in IEC 62676-4 for describing what a camera can show about a person at a given distance.
Why do manufacturers' DORI distances differ from this?
Datasheet DORI figures are usually measured at the narrowest zoom or in ideal lighting. This calculator gives the geometric result for the field of view you enter, which is the figure to plan against.
Does a higher-resolution camera always see further?
Only at the same field of view. An 8MP camera with a wide 2.8 mm lens can have less pixel density at 10 m than a 4MP camera with a 6 mm lens. Lens choice usually matters more than megapixels.
Is pixel density the only factor?
No. Low light, motion blur, backlight and compression all reduce usable detail. Treat these distances as the best case and add margin for night-time and backlit doorways.