Camera configuration
Quick configurationTarget dimensions
Dimension used for DRIDetection
910 mTarget presence can be detectedRecognition
228 mTarget class can be recognizedIdentification
114 mTarget details can be identifiedIFOV
1.319mrad / pixelHorizontal FOV
45.76°degreesVertical FOV
37.31°degreesDiagonal FOV
56.77°degreesProjected pixel size (GSD)
131.87mm / pixelScene width
84.40mScene height
67.52mScene diagonal
108.08mReference result. Engineering estimate — validate the final lens, detector, atmosphere and image-processing chain in real conditions.
Reference guide
Thermal camera formulas explained
Use this calculator to compare modules and lenses consistently. Results are geometric estimates, not guaranteed operational performance.
Johnson DRI range
R = (Target × Focal) ÷ (Pitch × Pixels)Range is estimated from focal length, target dimension, pixel pitch and the required pixels across the target. This tool uses 1.5 pixels for detection, 6 for recognition and 12 for identification.
IFOV and field of view
FOV = 2 × atan(Sensor ÷ 2F)IFOV is pixel pitch divided by focal length. Horizontal and vertical FOV use the exact sensor-size geometry rather than a small-angle shortcut.
Scene coverage
Width = 2D × tan(HFOV ÷ 2)At a known distance, scene width and height are calculated from the horizontal and vertical field of view using the triangle theorem.
Selection workflow
How to use the result for module selection
- 1Enter the detector resolution, pixel pitch and lens focal length from the module specification.
- 2Use realistic target dimensions and compare DRI thresholds rather than relying on detection range alone.
- 3Check scene coverage and GSD at your actual working distance, then validate with a sample.
Continue your thermal imaging evaluation
FAQ
Thermal imaging calculator FAQ
What is the difference between detection, recognition and identification?
Detection indicates that a target is present. Recognition estimates whether its general class can be distinguished. Identification requires more pixels and aims to reveal defining details.
Are Johnson DRI distances guaranteed?
No. They are geometric planning estimates. Atmosphere, target contrast, optics, detector sensitivity, stabilization, display scale and image processing can materially change usable range.
What does IFOV mean for a thermal camera?
Instantaneous field of view is the angle represented by one detector pixel. A smaller IFOV normally means finer spatial sampling at the same distance.
Should I choose a longer focal length for more range?
A longer focal length can improve target sampling and DRI range, but it narrows field of view. The correct lens balances range, coverage, payload size and tracking requirements.