From:	David Woods <david@*******.FREESERVE.CO.UK>
Subject:	Re: thermographic vision-question
Date:	Wed, 3 Feb 1999 18:40:33 +0000

Marc Renouf wrote:
>
> On Wed, 3 Feb 1999, ArcLight wrote:
>
> > What about this situation: some guard hides behind a wall, as you hosed
> > enough lead to his direction that he dived into cover. So he is, as I said
> > before, behind a wall. Now, if he is in physical contact to him, eg not
> > just standing there but leaning to that wall, would he reveal his position
> > by changing its temperature? How long would this take?
>
> Like I said before, it depends on the thickness of the wall and
> what it's made of. For something like a typical cinder-block exterior
> wall, it would take a few minutes, especially because they tend to be
> filled with insulating foam, something that takes a while to bleed heat
> through. If it's something like a carpet-backed plywood cubicle wall, it
> may only take a few seconds.

The surface temperature of a human is very dependent on ambient
temperature. In the average run most people will be wearing clothes :).
So the surface in contact with the wall will be fairly close to ambient,
not blood temp.

Imo very little heat would be transferred to the wall. It would be tens
of minutes before a noticeable change was seen. IR cameras are used to
find people under collapsed buildings, so it is possible. I just does
think it would be any use during a fire fight.

Regards

- David Woods