At 02:48 PM 9/11/99 -0700, Robert J. Bradbury wrote:
>I think you need to study some physics about
>light, heat and reflections.
>The infrared enegy coming off of an object sitting
>in the sun can be *alot* greater than the infrared
>energy it receives. The object absorbs the visible
>light energy and re-emits it in the infrared.
>Why do you think black tar or sand gets *hot*?
>The amount of IR emitted by the object is going
>to be proportional to its absorbance of other
IAN: Reflected visible light from the sun is NOT infrared radiation, yet you errantly think that because a body radiates IR an FLIR can pick up the visible light of the reflection, it does not. The visible radiation reflecting off a body is not going to be much hotter than the IR radiaton coming off the body, which is why the FLIR did not pick up reflections off the body of water * from any angle * Hello!
>I would leave the determination of reflections vs.
>gun muzzle flashes to people who are trained to
>interpret FLIR images.
IAN: Hubba hubba. Fine, then listen to Doctor Edward Allard, who not only worked much of his life for the military in IR imaging but also holds patents in IR-imaging technology:
"...materials which reflect sunlight and thus seem bright in the visual spectrum will often appear indistinct, or even dark, to a thermal imager; the very reflective properties that make them bright to the eye make them appear cool, and thus dark, to FLIR systems. Interpretation of thermal images requires a knowledge of the reflective properties of both natural and man-made objects."