With respect to accuracy statements, it is also important to note that manufacturers test infrared instruments under laboratory conditions using high-emittance, blackbody simulators in a controlled environment. As a result, manufacturers derive accuracy specs under ‘best case’ conditions which may not be possible to duplicate in a given work environment.
To help ensure measurement accuracy, thermographers should:

• Always measure perpendicular to the target
• Correctly set radiometer inputs for emittance, reflected temperature, distance, and humidity
• Ensure target size is adequate for subject radiometer’s spot measurement size

Lastly, real-world challenges can create situations where it is not possible to measure temperatures to the accuracy level promised by an instrument’s spec sheet. These challenges include, but are not limited to, hot or cold ambient temperatures, and the use of different lenses or filters. Whenever accurate infrared temperature measurement is not possible, one should consider using contact thermometry instead.

• When using spray paint to mark at ground level, use a spray paint and dispenser designed for the task
• Make sure surfaces to be marked are clean and dry and will not be damaged by spray paint
• Never spray paint where wind may carry paint to unintended surfaces

When outlining the perimeter of an exception, use a series of dots to outline the most prominent features of the exception. These dots can then be connected with a solid line once their location is deemed satisfactory. Depending upon weather and target conditions, spray painted lines will often show clearly within the thermal image.