Understanding Building Infrared Imagery

Infrared imagery is often a grayscale picture whose scales (or shades of gray) represent the differences in temperature and emissivity (opposite of reflectivity) of objects in the image.  As a general rule, objects in the image that are lighter in color are warmer, and darker objects are cooler.  No object in the images is detected via visible light wavelengths (400-700 nanometers) rather, only from infrared wavelengths in the 3000-5000 nanometers or 3-5 micrometers (microns) range.  Lights and other relatively hot objects are very evident, but as a result of their heat--not light emissions.

When an image is taken with an infrared camera, it is often recorded onto videotape and digitally saved to an on-board PCMCIA card.  The image may be then modified in a number of ways to enhance its value to the end user.  In the case of the printouts enclosed with this package, the building images were digitized, saved and converted to .tif images through the use of Inframetrics Thermotechnix Thermonitor Pro software, then adjusted for color, contrast and brightness before being scaled and placed in a PowerPoint file.  The file was then printed on photographic paper by using a high quality ink-jet printer.  Also, images were recorded on digital videotape via S-video direct cabling, then recorded onto a videotape.

After sunset, wall areas that contain grout are a different color because the heat (from daylight sunshine and the resulting thermal change) radiates from these areas longer than those areas with empty or insulated cells.  When the building structure cools down, we scan the walls with a sensitive infrared camera to detect the sources of heat and record them for later analysis.  Since we can "see" all areas with more mass (filled cells) we can immediately determine if there is grout missing.  When structural deficiencies are found, we make a matching visual image with a digital camera for reference.