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I am challenged with a task of detecting a human from behind the glass. Could you please suggest what kind of sensor will be a good fit for the job?

A sensor can only be mounted on the inside of the glass panel approximately 1 meter above the head or at the knee level.

How do I detect if there is anyone standing in the immediate proximity from the glass panel on the other side?

enter image description here

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    \$\begingroup\$ Instead of dumping your challenge to let others do your challenge, have you already some ideas to solve this? \$\endgroup\$ Sep 5, 2015 at 3:23
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    \$\begingroup\$ "Obviously" a camera and something running OpenCV (or SimpleCV) in some form or another. \$\endgroup\$
    – vicatcu
    Sep 5, 2015 at 4:07
  • \$\begingroup\$ The only thing I can think of is a camera. \$\endgroup\$
    – user57037
    Sep 5, 2015 at 4:49
  • \$\begingroup\$ This is a valid, on-topic question, so what's the rationale for wanting to close it? \$\endgroup\$
    – EM Fields
    Sep 5, 2015 at 7:46
  • \$\begingroup\$ The most obvious answer (PIR sensor) won't work since most glass and IR-transparent plastic is opaque to far IR (10um-ish). Second most obvious- camera and software- might work- what if the human is wearing a Dalek (or bear) costume, for example? \$\endgroup\$ Sep 5, 2015 at 10:24

2 Answers 2

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If the glass is IR transparent and the only moving thing on the other side of the glass is warm-blooded, you could use a passive infrared (PIR) motion detector.

If the glass isn't IR transparent (or even if it is) you could use an LDR configured to detect fast-ish changes in illumination from the other side of the glass.

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Possibly by change in capacitance as the human gets close. Coat the inside of the window in conductive transparent "paint" and use a high frequency oscillator and look for a change in current taken by the "coating" as the human approaches. It's just a possibility to try out using a sheet of tin foil to see if it works.

If it works then a bear would also trigger a detect and because you live in Canada this may invalidate the idea.

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