The observation area of a point target, which is usually inaccessible,
is a necessary condition when utilizing the conventional single-band
infrared radiometric thermometry method, as the image gray level
inevitably undergoes dispersion. Otherwise, significant
errors will be generated, seriously affecting the applicability of
infrared radiometric thermometry for distant point targets in the
external field. To address the above issue, the infrared radiometric
thermometry method for point targets has been researched. A point
target radiometric thermometry method based on dual-band infrared
imaging is proposed, which can effectively measure radiance and
temperature when the area of the point target is unknown. The
experimental results show that, compared with conventional single-band
algorithms, the proposed dual-band point target thermometry algorithm
has a maximum error of 11.18°C under the condition of unknown area,
which can meet the needs of infrared radiometric thermometry of point
targets at long distances in the external field.