When to use: Use this designer to size a multi-camera CCTV layout. For each camera it computes the lens field of view from FOV = 2·atan(d / 2f), the horizontal coverage width at the working distance, and the resulting pixel density — then classifies it against the EN 62676-4 DORI levels (Detection 25, Observation 62.5, Recognition 125, Identification 250 px/m). The site overlap analysis sums per-camera coverage against the area you need to cover and recommends how many cameras achieve your target DORI level. Real coverage also depends on mounting height, tilt, and obstructions.
| Camera | Type | Focal | HFOV | Coverage @ D | px/ft | px/m | DORI |
|---|---|---|---|---|---|---|---|
| Cam 1 — Entry | Fixed | 4 mm | 70.0° | 42.0 ft | 63 | 208 | Recognition |
| Cam 2 — Lot | Varifocal | 2.8–12 mm (4.3×) | 91.6°–27.0° | 123.4–28.8 ft | 31 | 100 | Observation |
| Cam 3 — Overview | Fisheye | 1.4 mm | ~180° | 78.5 ft | 42 | 136 | Recognition |
This tool calculates field of view, coverage width, and pixel density for multiple cameras simultaneously and analyzes whether the combined camera placement achieves the required EN 62676-4 DORI level across a specified site width. Engineers use it to optimize lens selection and camera count for any surveillance zone.
For each camera, horizontal field of view is computed using FOV = 2 × arctan(sensor_width / (2 × focal_length)). Coverage width at the working distance is Width = 2 × Distance × tan(HFOV/2). Pixel density is horizontal pixel count divided by coverage width, converted to pixels per meter to classify the DORI level (Detection 25 px/m, Observation 62.5, Recognition 125, Identification 250 per EN 62676-4).
Varifocal and PTZ cameras show a coverage range from wide (minimum focal length) to tele (maximum focal length). Pixel density uses the wide-end setting as the worst-case scenario. Fisheye cameras use approximately 180° horizontal FOV with a half-circumference coverage approximation at distance.
The site overlap analysis sums all individual camera coverage widths and compares the total to the site width to check for coverage gaps. The recommendation function calculates how many cameras of the primary camera type are needed to cover the entire site width at the target DORI level.
EN 62676-4 (IEC 62676-4) defines the DORI pixel density thresholds for surveillance system performance evaluation: Detection 25 px/m, Observation 62.5 px/m, Recognition 125 px/m, Identification 250 px/m. These thresholds are the primary design criteria for professional CCTV specifications across the UK, EU, and increasingly adopted globally. ONVIF Profile S and Profile T specify minimum video quality and streaming requirements for interoperable IP camera systems.
Coverage calculations assume cameras point perpendicular to the target plane at the stated distance. Mounting height and camera tilt reduce effective horizontal coverage width at ground level — for high-mount cameras, account for the geometric projection of the FOV onto the floor plane. Overlapping camera coverage of at least 20–30% between adjacent cameras is recommended to eliminate handoff gaps and provide redundancy.
Fisheye cameras provide wide coverage but have low pixel density per zone due to the de-warping spread. They are best suited for overview detection zones, not identification. For mixed systems, classify each camera independently and ensure high-priority zones (entrance, cash office) are covered by cameras that achieve at minimum Recognition (125 px/m) at the target distance.
Enter the site width to cover and select the target DORI level. Add cameras with their type (fixed, varifocal, fisheye, PTZ), sensor format, focal length(s), resolution in megapixels, and working distance. The per-camera results table shows FOV, coverage width, pixel density, and DORI level for each camera. The site overlap analysis shows total coverage, gap or overlap versus site width, and the recommended camera count to achieve the target DORI level across the full site.
Recognition requires 125 px/m. Enter your camera spec and target distance in the calculator — the recommended camera count field automatically calculates how many of the primary camera type are needed to cover 200 ft at Recognition. A 4MP camera with a 4 mm lens at 40 ft typically covers 35–40 ft at Recognition, requiring 5–6 cameras for 200 ft.
Detection (25 px/m) is sufficient for general presence detection in large parking areas. Recognition (125 px/m) is typically specified for entrances, exit lanes, and areas where vehicle occupant identification may be needed. Identification (250 px/m) is specified at payment kiosks and access control points.
Fisheye cameras cover wide areas but provide low pixel density per zone, typically achieving Detection or Observation but rarely Recognition at practical ranges. Use fisheye cameras as overview cameras for large open areas where presence detection is sufficient, supplemented by fixed cameras covering high-value zones at higher DORI levels.
Varifocal cameras have a manually adjustable focal length set during installation — they provide a fixed FOV in operation. PTZ (Pan-Tilt-Zoom) cameras can change FOV in real time under operator or automated control. For coverage design, a PTZ is planned at its wide-end FOV (worst-case pixel density) for continuous monitoring; the tele end is used for investigation or zoom-in on events.
This tool calculates horizontal FOV assuming perpendicular view of the target plane. For cameras mounted high and tilted down, multiply the calculated coverage width by cos(tilt_angle) to get effective ground-plane coverage. A camera tilted 30° down covers cos(30°) = 87% of the horizontal distance calculated at the stated mounting height.
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