Tools · EO/IR payloads

DRI range calculator

Detection, recognition and identification ranges of an EO/IR camera, computed from its sensor and optics, with the assumptions behind every figure.

STANAG 4347
Defence NATO reference for vehicles, and military practice for people: 1 / 3 / 6 cycles on the target.
IEC 62676-4
Civil Video-surveillance standard for people: pixels per metre needed to detect, recognise, identify.
Justified
A written justification of each result, ready to copy or print as a one-page report.

Example camera. Replace the values with your own: every result updates as you type.

Visible · 0.4–0.7 µm

Day channel

Include

Pixel pitch (µm) Focal length (mm) Aperture (f-number) Wavelength (µm) Horizontal pixels Demosaicing factor (colour sensor; 1 = no loss)

LWIR · 8–14 µm

Thermal channel

Include

Pixel pitch (µm) Focal length (mm) Aperture (f-number) Wavelength (µm) Horizontal pixels Sensor NETD (mK)

Pixels on target

Targets and criteria

Criteria of the selected targets. Cycles: pixels across the critical dimension (2 pixels = 1 cycle). IEC 62676-4: pixels per metre on the person.

Size (m)Detect.Recog.Ident.

Optics and environment

Degradations

Optical diffraction Stabilization residual (µrad) Include atmosphere

Atmosphere, day channel

Meteorological visibility (km) Target inherent contrast Contrast threshold

Atmosphere, thermal channel

LWIR extinction (per km) Target-to-background ΔT (K, STANAG 4347: 2) Threshold (multiple of NETD)

Results

Ranges (km)

Check requirements

Reference targets

Optional targets

Each range is the shorter of the geometric range (enough pixels on the target) and the atmospheric limit of the channel. The two person columns answer different questions: military practice (defence) counts cycles on the silhouette, IEC 62676-4 (civil video surveillance) asks for enough detail to see and identify an individual, which is far more demanding. No standard defines drone targets: their sizes are examples, their criterion is the STANAG one. Tick Check requirements to enter a required range under each result; entries stay in this browser only.

Generated from your inputs

Justification

Conventions

Vehicle, NATO STANAG 4347 Defence. Nominal static range performance of thermal imagers for ground targets: standard target 2.3 × 2.3 m (main battle tank, front view), 1 / 3 / 6 cycles for detection, recognition and identification, 2 K target-to-background difference. Applied here to the day channel as well, as NATO has no equivalent for visible cameras.
Person, military practice Defence. STANAG 4347 defines no person target. Defence EO/IR datasheets commonly apply the same 1 / 3 / 6 cycles to a standing person of 1.8 × 0.5 m, with a 0.75 m critical dimension.
Person, IEC 62676-4:2014 (DORI) Civil. Video-surveillance standard defined for people: 25 px/m to detect a person, 125 px/m to recognise someone already seen, 250 px/m to identify an individual (plus 63 px/m to observe, not shown). The range does not depend on the target size. The 2025 edition replaces these levels with seven new categories, not modelled here.
Drones and custom targets. No standard defines them: the STANAG 1 / 3 / 6 cycles are applied to the size you enter.

Method and limits

Pixel field of view IFOV = pixel pitch / focal length, divided by the demosaicing factor on a colour sensor; diffraction 1.22 × λ × N / focal length; stabilization residual added in quadrature.
Cycles: R = critical dimension / (pixels × system IFOV). Pixel density: R = 1 / (density × system IFOV).
Atmosphere: day R = V / 3.912 × ln(C0 / Cthreshold) (Koschmieder); thermal R = ln(ΔT / (k × NETD)) / σ.
A nominal static estimate, not a measured performance: turbulence, lens MTF beyond diffraction, day-channel noise, video compression and observer performance are not modelled. Confirm on a bench (resolution, NETD) and in the field at surveyed distances.