DORI (IEC 62676-4) Explained: Pixels per Metre, Datasheet Distances and What a Factory Needs
DORI is the 2014 edition of IEC 62676-4: Detect 25, Observe 62.5, Recognise 125 and Identify 250 pixels per metre on the target. A datasheet "DORI distance" is how far away the camera still delivers that density at the centre of the image. On a factory floor, plan below it: for five Indian camera-lens variants, printed distances are 5–47% longer than their own printed field of view gives.
Verified against
- IEC 62676-4:2025, ed. 2.0, published 9 Oct 2025 (IEC webstore). The foreword and table of contents come from the public preview of STN EN IEC 62676-4:2026 (Slovak standards office preview).
- Axis Communications white papers: Pixel density based on IEC 62676-4:2014 (Apr 2026 ed.) and Pixel density based on IEC 62676-4:2025 (Sep 2026 ed.).
- Omada (TP-Link) "What is DORI?".
- Datasheets: CP Plus CP-UNC-TA21L3C-Q (published 05-08-2026), Matrix SATATYA CIBR20FL36CWP P2 (linked from Matrix technical specifications), Prama PT-NC320P1-N(D2) product spec page.
- Checked 13 Oct 2026.
- The level names below come from Axis.
DORI levels and the 2025 replacement
| Level (2014 "MDORII") | px/m | px across a 16 cm face | What the operator can do (Axis wording) | Source |
|---|---|---|---|---|
| Monitor | 12.5 | 2 | not defined in the public sources we read | IEC foreword |
| Detect | 25 | 4 | "determine whether or not any individual is present" | IEC foreword, Axis 2014 |
| Observe | 62.5 (Axis prints 63, Omada 62) | 10 | "determine how many people are present and to see characteristic details" | same |
| Recognise | 125 | 20 | tell "whether or not an individual shown is the same as someone they have seen before" | same |
| Identify | 250 | 40 | "identify an individual" | same |
| Inspect | 1000 | 160 | not defined in the public sources we read | IEC foreword |
The standard's foreword gives only the acronym "MDORII"; "Monitor" and "Inspect" are the commonly used names for the first and last levels. Axis bases the face column on the assumption that "an average human face has a width of 16 cm". The edition-2 foreword describes a "complete redefinition of pixel densities": the six-level MDORII scale becomes the seven-level O2DCPVS scale, and "this second edition cancels and replaces the first edition published in 2014" (IEC foreword).
| 2025 level (Axis names) | px/m | px/face | Group |
|---|---|---|---|
| Overview | 20 | 3 | LPDO |
| Outline | 40 | 6 | LPDO |
| Discern | 80 | 12 | LPDO |
| Perceive | 125 | 20 | HPDO |
| Characterize | 250 | 40 | HPDO |
| Validate | 500 | 80 | HPDO |
| Scrutinize | 1500 | 240 | HPDO |
Source: px/m from the IEC foreword; names, px/face and the low/high pixel-density-object grouping from Axis 2025. The standard gives no one-to-one mapping from the old levels to the new ones. In Slovakia the old EN 62676-4 is withdrawn from 30 Nov 2028, per the national adoption notice. Indian datasheets still print the 2014 levels.
How vendors get the "DORI distance" in a datasheet
The geometry is simple. Scene width at distance d is 2·d·tan(HFOV/2). Divide the horizontal pixel count by that width to get px/m. Turn it around and the maximum distance for a level is pixels ÷ (px/m × 2·tan(HFOV/2)).
Axis states that its datasheet DORI calculations "use the center of the image as the reference point and consider lens distortion" (Axis 2014). Omada calls each value "the maximum distance… at which the camera can achieve the corresponding DORI level" (Omada). CP Plus, Matrix and Prama publish no method.
We put each vendor's printed resolution and horizontal angle of view into the formula:
| Camera (as printed) | Pixels × HFOV | Printed D/O/R/I (m) | From printed HFOV (m) | Printed ÷ computed |
|---|---|---|---|---|
| CP Plus CP-UNC-TA21L3C-Q, 3.6 mm | 1920 × 86° | 52.4 / 21.0 / 10.5 / 5.2 | 41.2 / 16.5 / 8.2 / 4.1 | ×1.26–1.28 |
| Matrix CIBR20FL36CWP P2, 3.6 mm | 1920 × 87.5° | 50 / 21 / 11 / 5 | 40.1 / 16.0 / 8.0 / 4.0 | ×1.25–1.37 |
| Prama PT-NC320P1-N(D2), 2.8 mm | 1920 × 103° | 45 / 18 / 9 / 4 | 30.5 / 12.2 / 6.1 / 3.1 | ×1.31–1.47 |
| Same Prama, 4 mm | 1920 × 83° | 56 / 22 / 11 / 5 | 43.4 / 17.4 / 8.7 / 4.3 | ×1.15–1.29 |
| CP Plus CP-UNC-TA41L6C-Q, 6 mm | 2688 × 49° | 124.0 / 49.6 / 24.8 / 12.4 | 118.0 / 47.2 / 23.6 / 11.8 | ×1.05 |
The gap need not be an error: a vendor may calculate from sensor and focal length, or at the image centre, where barrel distortion packs more px/m (our inference). It is widest on the widest lens. For planning, use the printed-HFOV figure, which is what the lens and DORI calculator does, and treat the datasheet number as the best case.
Where brands differ
- Observe value. The standard says 62.5 px/m, Axis prints 63 and Omada prints 62; immaterial.
- Labelling. Matrix names the standard on the datasheet. The CP Plus and Prama pages print "DORI" and the distances without saying which px/m or which edition they used.
- Varifocal models print two sets of distances, wide and tele. Prama PT-NC326P1-WNRAM(D2) lists 42.7–132 m Detect (Prama). Plan at the zoom you will set.
- Main stream vs sensor. The CP Plus 6 MP sheet gives effective pixels of 3200 × 1800 and a main stream of 3288 × 1850 (CP-UNC-TA61L3C-LQ). DORI depends on the stream actually used: a sub-stream sent to analytics has far fewer px/m.
What breaks in a factory
The standard itself goes beyond pixel count. Its table of contents has clauses on image compression (9.1) and frame rate (9.2), plus new Annex D tables on "number of frames depending on object speed" (IEC preview). Axis calls the pixel model "a simplified model of a complex reality" and names "light direction, optics quality, and image compression" as factors. On an Indian shop floor:
- Low light and slow shutter. The CP Plus sheet allows auto shutter down to 1/3 s and the Matrix sheet down to 1/15 s. In a dim bay, auto-exposure slows the shutter and anything moving smears, so a moving person gets less usable detail than the px/m number promises. Set a shutter floor (low-light guide).
- IR mode at night gives a monochrome image. A colour stack light then shows only brightness.
- 50 Hz mains and LED lighting can produce rolling bands that hide indicator lamps (flicker fix).
- Dust and oil film on the dome or lens window softens the whole image.
- Compression. Low bitrates and H.265 smart codecs smooth out fine detail, so the pixels may be there and the detail still lost.
- Edges and tilt. The datasheet figure is at the centre of the image. A machine at the edge of the frame, or seen steeply from a 6 m roof truss, gets fewer px/m.
Which level a factory owner actually needs
These are worked assumptions, not clauses of the standard. The public text has no levels for machines.
| Task | Level to plan for | Why |
|---|---|---|
| Is someone at the machine or in the bay? | Detect, 25 px/m | Matches the Axis definition of whether "any individual is present" |
| Count people in a line or zone | Observe, 62.5 px/m | Matches "determine how many people are present" |
| Machine running or idle: stack light, spindle, operator at station | Recognise, 125 px/m or more on the smallest indicator | Assume a 70 mm stack-light segment: 25 px/m puts about 2 px on it and 125 px/m about 9 px |
| Read a label, gauge or batch code | Beyond Identify; a close mount | Assume 10 mm characters: 250 px/m gives 2.5 px per character, while a face at Identify gets 40 px |
Size each position with the calculator, then write the px/m into the purchase order (tender template) and check it at handover (commissioning checklist).
When to call the installer / what to ask the vendor
Ask the vendor three things: which px/m and which edition its DORI row uses, whether the distance is computed at the image centre or across the full frame, and which stream resolution it assumes. Call the installer if a position only meets its level at datasheet distance, or if it fails the check at night in IR mode. Background: resolution and lens for a factory floor.
Mama reads a factory's existing cameras over RTSP/ONVIF and reports machine idle time to the owner. For that it needs Recognise-class pixels on the machine, not on faces (askthemama.com). Leave an email or phone in the form below.
FAQ
What is DORI in CCTV? DORI stands for Detection, Observation, Recognition and Identification. These are four pixel-density levels from IEC 62676-4:2014, at 25, 62.5, 125 and 250 px/m. Each level says what a human operator can tell about a person at that density.
How is DORI distance calculated? Divide the horizontal pixel count by the level's px/m times 2·tan(HFOV/2). Axis says datasheet figures use the image centre and account for lens distortion.
Is DORI still valid after IEC 62676-4:2025? The 2025 edition replaces the 2014 one and its scale. Its seven-level O2DCPVS scale has no official mapping to DORI; Axis's Validate level, used to check known individuals, is 500 px/m. Indian datasheets still print 2014 DORI: a yardstick, not the current IEC text.
What is the difference between DORI and PPM? PPM (px/m) is the measurement; DORI names four PPM thresholds tied to tasks.