PIVOT-IR USER MANUAL
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9-1 Introduction to Radiometry
The basic reason for employing image processing programs when analyzing IR
images is to have a fast and comprehensive means to determine the information
content of an image in numerical terms. Radiometry is considered the base from
which to conduct this analysis.
Typically, converting the gray scale values to values of temperatures requires
either a calibration of individual cameras or field calibration data. The method
for calibrating images provided in this program is field calibration data because
temperature data is stored within the media loaded into the software and read
by the software program.
IR Tools looks for a data stored within the media. If this software cannot read any
calibration data, the user cannot perform temperature analysis on the data. This
typically occurs when non-radiometric images are opened using the software.
Contact customer service if there is an issue. To adjust parameters see
Section
8-13 Thermal Analysis.
9-2 Emissivity
All objects radiate infrared energy. The amount of energy radiated varies based
on the actual surface temperature and the surface emissivity of the object. The
Thermal imager senses the infrared energy from the surface of the object and
uses this data to calculate an estimated temperature value.
Many common objects and materials such as painted metal, wood, water, skin,
and cloth are particularly good at radiating energy and it is easy to get relatively
accurate measurements. For surfaces that are good at radiating energy (high
emissivity), the emissivity factor is >=0.90. This simplification does not work on
shiny surfaces or unpainted metals as they have an emissivity of <0.6. These
materials are not good at radiating energy and are classified as low emissivity.
Adjust the emissivity setting according to
Section
8-13-2 Emissivity.
A LIST OF COMMON EMISSIVITY VALUES CAN BE FOUND ON THE NEXT PAGE.
9
Radiometry
SURFACES WITH AN EMISSIVITY OF < 0.60 MAKE RELIABLE AND CONSISTENT
MEASUREMENTS PROBLEMATIC. THE LOWER THE EMISSIVITY, THE GREATER
POTENTIAL FOR ERROR WITHIN THE DEVICE’S CALCULATIONS. ERRORS MAY
STILL OCCUR EVEN WHEN ADJUSTMENTS ARE PERFORMED PROPERLY.
