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Detection · Recognition · Identification range for any electro-optical or thermal sensor

DRI Range Calculator

This tool needs JavaScript to change the settings. The table below is the result for the default configuration.

Camera: drag for heightTarget: drag for range

14 m
Identify
50 m100 m200 m500 m1 km2 km5 km10 km20 km1,4 kmhorizonatmosphere
  • Identify
  • Recognise
  • Detect
  • Sensor could resolve it — atmosphere or horizon prevents it

Sensor eye schematic

The scene needs JavaScript. Every range it draws is in the table below.

23,8px across the critical dimension

Target

Zoom 100 mm

9502008002000

Weather

Playing with

Sensor

aWhat kind of sensor?

bDetector

cLens focal length

 

Quick add

dOptional detail

Targets

Custom

Task and conditions
Probability of success

Sensor height above ground
Atmosphere

Model settings

These change how the model works rather than what you are measuring. The defaults are the usual conventions; every one of them is stated on the result so a reader knows what they are looking at.

Criteria convention

Critical dimension
Horizon refraction model

d [km] = k (√h_sensor + √h_target). 3.57 is the true geometric horizon; 3.86 adds the standard optical and infrared refraction (k ≈ 7/6) and is the right default here; 4.12 is the 4/3-earth radar convention and is optimistic for an imaging sensor.

ΔT₀ and the ×NETD threshold drive thermal bands; the contrast threshold and airlight ratio drive SWIR, NIR, visible and intensified bands. Both thresholds are scaled by the task’s cycle count as a first-order stand-in for MRTD and MRC rising with spatial frequency — replace them with measured curves before using this for anything contractual.

σ presets are visible-band extinction coefficients. Published field data puts LWIR range in category-II fog at roughly four times MWIR, which would correspond to an LWIR multiplier well below 1 in the fog presets. The default is left at 1.00 because band-resolved coefficients need MODTRAN-class data; set it deliberately rather than inheriting a guess.

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Full matrix

SensorBandf
mm		Resolution
cyc/mrad		Detect
km		Recognise
km		Identify
km		Limited by
Human · 1,8 × 0,5 m
LWIR 640×512 · 12 µmLWIR502,082,640,6590,329Sensor
MWIR 640×512 · 15 µmMWIR1003,334,221,050,527Sensor
Light vehicle · 1,4 × 4 m
LWIR 640×512 · 12 µmLWIR502,086,571,640,822Sensor
MWIR 640×512 · 15 µmMWIR1003,3310,52,631,31Sensor
Main battle tank · 5 × 5 m
LWIR 640×512 · 12 µmLWIR502,0813,93,471,74Sensor
MWIR 640×512 · 15 µmMWIR1003,3318,85,562,78Atmosphere
Class-I UAV · 0,3 × 1 m
LWIR 640×512 · 12 µmLWIR502,081,520,380,19Sensor
MWIR 640×512 · 15 µmMWIR1003,332,430,6090,304Sensor

Resolution is given in cycles per milliradian because that is the one quantity a sampled array and an intensifier tube can be compared on — for an array it is f / (2 × pitch), for a tube it is f × lp/mm. Ranges use 1.5 / 6 / 12 pixels — 0.75 / 3 / 6 cycles at 50% probability.

Full matrix

Optics summary

The same answer under other conventions

All calculations run in your browser. Nothing is sent to Inventra.

This tool uses a geometric Johnson-criteria model with an NVESD target transfer probability function, optional Beer–Lambert atmospheric attenuation, a diffraction ceiling and a refracted-horizon limit. It is not TRM4, NV-IPM or STANAG 4347 — those are measurement-based models and are licensed or export-controlled. Real performance depends on target contrast, background clutter, scene temperature, operator training and the atmosphere on the day.

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