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RE: [SeattleRobotics] Re: PIR Sensor Modification

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  • Alan Marconett
    Seems like someone would want to rasterize the data coming from a PIR, much like from a camera. Then CV could process it, and define little rectangles to
    Message 1 of 31 , Apr 30, 2009
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      Seems like someone would want to rasterize the data coming from a PIR, much
      like from a camera. Then CV could process it, and define little rectangles
      to track the desired object (once trained). Saw a good demo at the
      HBRobotics club meeting last night!

      It was funny, sometimes the camera would ketch a glimpse of Wayne, and would
      stop tracking the speaker, and follow Wayne! Apparently the face
      recognition algorithm liked Wayne's face better ?!

      Alan KM6VV

      > -----Original Message-----
      > On Behalf Of Dennis Clark
      >
      > I can see this working. It doesn't matter whether the sensor moves and
      > sees a change in heat or the person moves and the sensor sees a change
      > in heat. The sensors are usually tuned to human body temperature so
      > just a background heat difference wouldn't trigger it (unless it was at
      > body temperature). If you pointed the sensor, then if something was
      > there, you'd trigger it, the motion caused the differential. I wouldn't
      > think that it'd be all that accurate, but it should still work. What an
      > interesting project!
      >
      > IMO,
      > DLC
      >
    • dan michaels
      ... I favor your scenario over Peters. :) ... I wish I knew. Supposedly, frogs can only see moving objects [or at least they only respond to such].
      Message 31 of 31 , May 2 3:11 PM
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        --- In SeattleRobotics@yahoogroups.com, "David Buckley" <david@...> wrote:
        >
        > Peter
        > Surely a non scanning PIR on a robot creeping towards you is exactly the same as you creeping towards a non scanning stationary PIR operating your kitchen lights. As long as something moves and the animal image is big enough and crosses a boundary then the PIR wiil see it.
        > If the robot is heading for somone then eventuall the image will grow to a size which will cross a boundary.
        >


        I favor your scenario over Peters. :)


        >
        > A bit like a frogs vision?
        >
        > Hmm a question Dan, when a frog is moving about does its vision system switch into a different mode so that it can see staionary objects?
        > David
        >


        I wish I knew. Supposedly, frogs can only see moving objects [or at least they only "respond" to such]. Supposedly they starve in the midst of piles of dead flys [those old time researchers were kind of whimsical].

        However, my guess is that even frogs have a primitive form of "efference copy" such that self-generated movements inhibit the systems that normally respond to external movement. Otherwise, the frogs would be continually triggering their own predator-prey behaviors whenever they so much as twitch.

        In olden times, there was a lot of neurophysiology work done on the frog/toad optic tectum [the major predator-prey detection area, eg David Ingle, J-P. Ewert, Jerome Lettvin et al], but a few studies also showed there was an inhibitory loop involving the tectum and diencephalon [primitive thalamus], but I don't remember the details.
        So, the basic connections are there for efference copy/etc.

        [also, no reason not to make up something that sounds reasonable and stick it on a robot :)].
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