[GRLUG] OFF TOPIC - Speaking of Infrared...

[Michael Mol]

On 1/28/2010 8:48 PM, Bob Kline wrote:
> How cool was the room?

Thermostat is normally 72F, but that's in another room. I'm in the room 
with the servers, which is usually about five higher.

>
> You seen to have a short sleve
> shirt on, but I think I can see the
> back of a chair,  walls in the the
> background.  Is it a big room?

I wear short-sleeves year-round, primarily because of the higher 
temperatures in the vicinity of my workstation. That was actually taken 
in Dec of 2007, I think. (The date is off on Flickr, but that's because 
the source is a BMP, and the timestamp was screwed up due to a few 
workstation migrations.)

Room is about 750 ft^2, or about 6000ft^3.

>
> Jet gets to the fact that because
> you stand out some the room might
> be large, and-or cool

I don't think you understand how far-IR temperature monitoring works. 
If you'd like, I can delve into a discussion of microbolometers and 
measurement adjustments stemming from surface emissivity, ambient 
temperature and ambient humidity values.

There's more at work than just the wavelength of quanta, there's also 
intensity of emissions, considerations of atmospheric absorption and 
considerations of ambient temperatures reflecting off of other surfaces.

What it boils down to is that in practical conditions, I can (and do, 
for use cases such as those that that software was written for) measure 
surface temperatures to within 0.01C.

Don't forget I also control the palettization -- the conversion of raw 
temperature numbers to RGB pixels, which goes towards making differences 
"stand out."

>
>      -- Bob
>
>
> On Thu, Jan 28, 2010 at 8:18 PM, Michael Mol <mikemol at gmail.com
> <mailto:mikemol at gmail.com>> wrote:
>
>     On Thu, Jan 28, 2010 at 8:02 PM, Bob Kline <bob.kline at gmail.com
>     <mailto:bob.kline at gmail.com>> wrote:
>      > On Thu, Jan 28, 2010 at 6:03 PM, Michael Mol <mikemol at gmail.com
>     <mailto:mikemol at gmail.com>> wrote:
>      >>
>      >>
>      >> The chief problem with "darkvision" as it applies to passive
>     near-IR is
>      >> that there is a lot of ambient near-IR radiation that's not
>     related to
>      >> warm bodies.
>      >>
>      >> In short, your warm body radiation in the near-IR will be there, but
>      >> largely drowned out by the ambient near-IR radiation.**
>      >
>      > The peak wavelength for a human body
>      > thermal spectrum is 10 microns - in the so
>      > called long-wave infrared range.  You shine
>      > if you're standing out in the snow,  but the
>      > human body is not really very hot.  About
>      > the same as your house interior, which is
>      > that temperature, by design. So you don't
>      > stand out much.
>      > See http://en.wikipedia.org/wiki/Infrared
>      >     -- Bob
>
>     http://www.flickr.com/photos/28208534@N07/3681419505/in/set-72157620862996406/
>
>     I don't?
>
> What kind of image is this?  i.e., how
> is it corrected?
>
>
>
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