ok kiddies: how about this:
How does an IR camera work?
Infrared Energy Detection
An infrared camera is a non-contact device that detects infrared energy (heat) and converts it into an electronic signal, which is then processed to produce cameraa thermal image on a video monitor and perform temperature calculations. Heat sensed by an infrared camera can be very precisely quantified, or measured, allowing you to not only monitor thermal performance, but also identify and evaluate the relative severity of heat-related problems.
http://www.flir.com/thermography/eurasia/en/content/?id=11460
Why measure temperature?
Infrared and Temperature Measurement
Finding a problem with an infrared camera is sometimes not enough. In fact, an infrared camera image alone without accurate temperature measurements says very little about the condition of an electrical connection or worn mechanical part. Many electrical targets are operating properly at temperatures that are significantly above ambient. An infrared image without measurement can be misleading because it may visually suggest a problem that does not exist.
Predictive Maintenance
Infrared cameras that incorporate temperature measurement allow predictive maintenance professionals to make well informed judgments about the operating condition of electrical and mechanical targets. Temperature measurements can be compared with historical operating temperatures, or with infrared readings of similar equipment at the same time, to determine if a significant temperature rise will compromise component reliability or plant safety.
Digital Image Storage
Digital image storage, available on most FLIR infrared cameras, produces calibrated thermal images that contain over 78,000 independent temperature measurements that can be measured at any time.
all content except for "ok kiddies ect" from the following site...
http://www.flir.com/thermography/eurasia/en/
now if you go to the site little haters, you will see pictures of the inside of buildings, thermography and how easy it is to determine where or what is inside of a structure... does it take an exact image of the inside of the structure? no but as all mammals radiate heat, it sure as heck can show the authorities what is inside a structure and if (off the top of my head) there is a highly concentrated source of heat (like a 1k lamp perhaps???) operating inside... btw: all that info is available AS THE FIRST SEARCH ON GOOGLE... sorry i didn't post earlier, i (unlike some of you it appears) have things to do, like errands and watering my plants... don't like it??? go f--- yourself... try to make our little electronic home a better one, jerks...