Field of View Calculator (Sensor + Focal Length) implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-181

Effect

Computation or source lookup only

Input and validation requirements

The zero-diagonal input causes the equivalent-focal-length calculation to divide by zero. The zero-width boundary also produces mathematically finite but physically invalid output, and a negative focal length yields signed negative AOVs unless explicitly rejected or normalized.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "sensor_width_mm": 36,
    "sensor_height_mm": 24,
    "focal_length_mm": 50
  },
  "expected_outputs": {
    "horizontal_aov_deg": 39.6,
    "vertical_aov_deg": 26.99,
    "diagonal_aov_deg": 46.79,
    "equivalent_focal_length_mm": 50.04
  },
  "working": "Diagonal=sqrt(36^2+24^2)=sqrt(1872)=43.2666 mm. Horizontal=2*atan(36/(2*50))*180/pi=2*atan(0.36)*180/pi=2*0.34556*57.2958=39.60 degrees. Vertical=2*atan(24/100)*180/pi=2*atan(0.24)*57.2958=2*0.23554*57.2958=26.99 degrees. Diagonal=2*atan(43.2666/100)*57.2958=2*atan(0.432666)*57.2958=46.79 degrees. Equivalent=50*(43.3/43.2666)=50.04 mm."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json