Radiometric Surface Physics // Protocol EMS-02
Emissivity Correction & True Temperature Calculator
Compute true surface temperatures from apparent thermal camera readings using the Stefan-Boltzmann radiosity inversion, surface emissivity (ε), and reflected background radiation.
0.70
0.05 (Polished Metal)0.60 (Oxidized)0.96 (Blackbody / Tape)
Uncorrected camera reading
Measured via crumpled aluminum foil
Radiometric Compensation Output
True Surface Temperature
80.2°C (176.3 °F)
Moderate Reflection Risk
Temperature Under-Reading
+15.2 °C
True vs apparent delta
Reflected Fraction
30%
Background reflectance
Raw Camera Value:65.0 °C (149.0 °F)
Background Reflection Temp:22.0 °C
Atmospheric Transmittance:0.98
Radiometric Transfer Physics
The Stefan-Boltzmann Radiosity Equation and Reflection
1. Total Radiation Received by Camera
An infrared detector measures radiant flux composed of three distinct physical contributions:
W_tot = ε · τ · σ · T_obj⁴ + (1 - ε) · τ · σ · T_refl⁴ + (1 - τ) · σ · T_atm⁴
When inspecting shiny bare metals with low emissivity (ε < 0.20), the camera primarily registers reflected heat from warm transformers, switchboards, or the thermographer's own body.
2. The Reflected Apparent Temperature (T_refl) Method
To calibrate T_refl accurately per ASTM E1862 standards:
- Crumpled Aluminum Foil Method: Crumple a sheet of aluminum foil, flatten it loosely onto cardboard, and place it in front of the target with emissivity set to 1.00.
- Measurement: The average temperature reading on the foil is your true Reflected Apparent Temperature (T_refl). Enter this into the camera before conducting electrical audits.