# Effectiveness of heat sensors in high temperatures?

**URL:** <https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221>\
**Category:** Factual Questions\
**Created:** [July 17, 2003, 7:50pm UTC](https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221 "2003-07-17T19:50:46Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Super\_Gnat](https://avatars.discourse-cdn.com/v4/letter/s/e274bd/32.png) [@Super\_Gnat](https://boards.straightdope.com/u/Super_Gnat)\
**Post date:** [July 17, 2003, 7:50pm UTC](https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221/1 "2003-07-17T19:50:46Z")

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Would heat sensors be able to see a person’s body heat if the person was the same temperature as the outside environment?

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**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\
**Post date:** [July 18, 2003, 9:41pm UTC](https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221/2 "2003-07-18T21:41:01Z")

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As I seem to remember, wasn’t this a device in the movie “The Thomas Crown Affair” -by raising the temperature of the gallery the heat sensors were disabled allowing the theft. This was then tried in a recent science-entertainment programme on UK TV - can’t recall the name but I think it worked, but not as well as the movie. The problem is that there are still heat variations, allowing motion to be picked up using IR sensitive cameras.

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**Author:** ![Zenster](https://avatars.discourse-cdn.com/v4/letter/z/cdc98d/32.png) [@Zenster](https://boards.straightdope.com/u/Zenster)\
**Post date:** [July 18, 2003, 10:08pm UTC](https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221/3 "2003-07-18T22:08:50Z")

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It depends upon the thermal sensing system being used. Atmospheric volumes will tend to have a much greater degree of thermal nonuniformity due to convection and turbulence. The human body’s core area is a much more stable heat source. It would be rather simple to acquire a human body’s thermal signature when compared with an atmospheric region.

If you had non-imaging thermal detectors, they might be aliased by elevating the ambient temperature to ~98.6° F. Any sort of imaging system, especially one with motion detection or segmented detector signal averaging probably would not.

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**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\
**Post date:** [July 18, 2003, 10:18pm UTC](https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221/4 "2003-07-18T22:18:30Z")

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Not sure about _The Thomas Crown Affair_, but the movie _Sneakers_ definitely had heating a room to body temperature to defeat thermal sensors in the plot.

“The girl with the uzi - is she single?”

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**Author:** ![Super\_Gnat](https://avatars.discourse-cdn.com/v4/letter/s/e274bd/32.png) [@Super\_Gnat](https://boards.straightdope.com/u/Super_Gnat)\
**Post date:** [July 19, 2003, 1:18am UTC](https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221/5 "2003-07-19T01:18:45Z")

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Thanks!

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**Author:** ![Sock\_Munkey](https://avatars.discourse-cdn.com/v4/letter/s/aeb1de/32.png) [@Sock\_Munkey](https://boards.straightdope.com/u/Sock_Munkey)\
**Post date:** [July 19, 2003, 8:03pm UTC](https://boards.straightdope.com/t/effectiveness-of-heat-sensors-in-high-temperatures/189221/6 "2003-07-19T20:03:27Z")

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I thought this thead was in reference to the movie “Predator”.