Presence sensing ...

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  • chris_j_hunter
    Automated Home Legend
    • Dec 2007
    • 1713

    Presence sensing ...

    I'm guessing inexpensive cameras (eg: 50GBP dome cameras) will be a useful addition for presence sensing ... and that maybe one per room, on the ceiling & near a corner, would be good, given unobstructed views ... with obstruction, some rooms might need two, or more ... ... but am I right ? Our card can cope with four cameras ... one in each main room, maybe ... is that going to be enough ? Has anyone actually tried augmenting reed-switches & PIRs with cameras, yet ??

    How about sound, too - dead-of night should be still & quiet, so noise & motion mea there's maybe a problem - what sort of camera- & sound-sensors might make sense ?

    Any thoughts ... ??
    Our self-build - going further with HA...
  • toscal
    Moderator
    • Oct 2005
    • 2061

    #2
    Motion detection on PC camera cards isn't the best. And may require quite a bit of tweaking to get right.
    Plus what is the frames or fields per second. The more cameras connected to the card the more this figure per camera drops. Unless each channel has its own processor.
    These are expensive but are supposed to be very good http://www.mobotix.com/eng_GB . Some of their cameras have multiple motion detection zones.

    Like many things a combination of things works best. Plus should one system fail you still have the other one.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
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    • Karam
      Automated Home Legend
      • Mar 2005
      • 863

      #3
      We generally recommend the IVC-200 capture card not for any reason other than we know it works and also has 4 independent digitiser channels so allowing 30fps on all channels simultaneously. As for motion detecion, well you should be able to see in Cortex help that there is fairly comprehensive functionality including a user selectable grid size and individually adjustable cell sensitivity as well as ability to filter in various ways but, as toscal has suggested, this just means more parameters to get right. For internal use the problems that are likely to come up are lights switching on and off which obviously have a dramatic effect on the image. For external use you get similar problems on bright, windy, part cloudy days, or if you have many trees in view (though if you're lucky you may be able to exclude the latter via the sensitivity grid).

      More useful might be some form of face recognition software so that cameras can be used to identify occupants passively, but I'm talking about the sort of thing that can identify faces from different angles and with an unstructured background and lighting. From what I have seen in recent years I think it has become feasible to do this but possibly requires some meaty computing resources?

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      • chris_j_hunter
        Automated Home Legend
        • Dec 2007
        • 1713

        #4
        goodness, face recognition, that seems ambitious !

        lights going on & off ... presumably, if Cortex was doing the switching, discounting would be possible - even automatic ?
        Last edited by chris_j_hunter; 2 January 2009, 06:50 PM.
        Our self-build - going further with HA...

        Comment

        • Karam
          Automated Home Legend
          • Mar 2005
          • 863

          #5
          Well I imagine that, like word recognition, if you're trying to distinguish between a small set (such as main occupants) then it may be easier and more reliable, but I can't say I've researched it so don't know what current state of play is - perhaps someone else in this forum might.

          Cortex accounting for light switch on/off? Yes I suppose it could, in a sense something like this is already done with light level sensing functions. But I still think for motion sensing the PIR is generally the more reliable, simpler, and cheaper option given the choice.

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