CCTV कैमरा लेआउट और कवरेज कैलकुलेटर

IEC 62676-4 is the part of the IEC 62676 Video Surveillance Systems for use in Security Applications standard that specifies application guidelines. It defines the Identification (≥250 px/m), Recognition (≥125 px/m), and Detection (≥62 px/m) pixel-density thresholds used to verify whether a camera placement achieves the required surveillance purpose. It supersedes earlier EN 50132-7 classification terminology in industrial and substation applications.

Identification (≥250 px/m) — sufficient resolution to identify an individual with high certainty, e.g., for forensic use or positive ID at an access gate. Recognition (≥125 px/m) — sufficient to recognize a previously known person, clothing, or vehicle type. Detection (≥62 px/m) — sufficient to detect the presence and direction of movement of a person or large object. Below 62 px/m the image quality is considered inadequate per IEC 62676-4 §5.3.3.

Camera count uses two bases: (1) Perimeter basis: cameras_perimeter = ⌈zone_length / (fov_width × (1 − overlap))⌉, and (2) Area basis: cameras_area = ⌈zone_area / (fov_width × fov_depth × (1 − overlap))⌉. The required count is the maximum of the two. If only one zone dimension is non-zero, the other basis returns 0 and is ignored. This approach covers both linear perimeter fencing and two-dimensional area surveillance.

IEC 62676-4 recommends a minimum 20% overlap (overlap_factor = 0.20) to avoid coverage gaps at zone edges caused by terrain, obstructions, or lens distortion at the periphery. For high-security perimeters with dense vegetation or uneven terrain, 30% (0.30) is common. Fisheye cameras with heavy barrel distortion may require up to 40% overlap because the effective px/m degrades significantly toward the image edges.

802.3af (PoE) delivers up to 15.4 W per port — adequate for fixed dome cameras up to ~12 W. 802.3at (PoE+) delivers up to 30 W per port — required for PTZ cameras (typically 20–25 W) and cameras with integral IR illuminators or heater assemblies. When the per-camera power draw (poe_camera_w) exceeds 15.4 W this tool flags a budget failure and recommends upgrading to 802.3at. IEEE 802.3bt (PoE++) delivers up to 90 W but is not yet modeled in this calculator.

A fisheye lens produces a circular image with severe barrel distortion. The nominal pixel-per-meter density at the image center is high, but it degrades rapidly toward the periphery. IEC 62676-4 px/m checks should be applied to the worst-case edge of the FOV, not the center average. This calculator uses the horizontal FOV width at the monitoring distance to compute px/m, which approximates the center-line value. For fisheye cameras with 180° FOV, the effective px/m at the image edge may be 3–5× lower than the center value — plan accordingly and apply generous overlap factors.