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Thread: Camera selection for face and iris capture at a distance

  1. #1
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    Camera selection for face and iris capture at a distance

    Dear all,
    I have a challenge to to consider about camera selection and I'm looking for the consultant from professionals:

    I'm going to build a camera system to capture iris of moving people from a distance of 5m. Captured iris will be analyzed and recognized to authenticate the identity of subjects.

    Requirement for iris camera is a 180pixels over the iris region, this number of pixel is required for possibility to analyzed and recognized the identity of subjects. I know that to capture that number of pixel at a distance of 5m, the camera should have very narrow Field of View to focus on iris region only and fast shutter to avoid motion blur when capturing small iris region. In addition, the lens need to be long (about 300mm).

    The problem is the same for face. I also want to capture face of moving people from a distance of 30m.

    I have two questions:
    1. Could you advise me which cameras, lens to use?
    2. About lighting, I have read something on using IR, NIR illuminators. What is the difference among those illuminators? In my case, which type of illuminator is suitable?

    Thanks

  2. #2

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    Re: Camera selection for face and iris capture at a distance

    so for some pizel resolution at a distance, you will be talking about finding some number of arc-seconds per pixel. Playing with a little maths and an FOV calculator shows that you are on the right tracks. a canon 500d (just an example chosen partly because its what i use, and partly because its got a fairly high resolution) with a 300mm lens (450mm at 35mm equiv) would give you about the angular resolution you are talking about. In terms of lightint, you can increase the ISO to get a faster shutter, and if you are only after the iris, you can probably get away with letting the aperture go wide open, those may be enough under reasonable lighting, especially since a camera would need a hard-hack to enable it to see any IR illumination.

    However, im sure iris recognition tech exists, i guess there must be some reason you cant just use one of them?

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    Re: Camera selection for face and iris capture at a distance

    Hi Kiennt,

    Welcome to the CiC forums and posing an interesting first question.

    It would be helpful to know where you are coming from?
    I'm probably more relaxed with my human liberties than some, but there is an element of wondering "who are we helping potentially 'spy' on us (me)" here.

    You don't say whether;
    - this needs to be realtime or 'shoot now, identify later' (good job we are talking photography here )
    - shooting will be handheld/human aimed, or a fixed camera on people passing through a narrow place
    - you already have a set of reference shots for ID, or will be building them up over time from other data gathered

    Hi Will,

    Thanks for starting this off (maths isn't my strongest point ).

    The 500D is 15MP, if I'm not mistaken, as it happens, I had a play with a friend's a couple of days ago, it seemed quite capable - nice bit of kit, especially with an EF 70-300mm on.

    Both,

    A couple of thoughts popped into my head reading the post and Will's reply;
    you can probably get away with letting the aperture go wide open
    This will require very good auto-focus performance, or possibly pre-focus if camera is fixed and trained on a doorway and reliably trigger shutter at the right time

    I have read something on using IR, NIR illuminators
    Is Iris recognition a monochrome technology? It will be if you illuminate like this
    What's NIR?

    Cheers,

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    Re: Camera selection for face and iris capture at a distance

    Thanks Will and Dave for your reply.

    First, about identity, I'm working in an university in Australia. I'm doing research on Iris recognition, trying to increase the distance of capture.

    About issues which Dave mentioned, this system should be realtime,which means Capture-Recognize-Capture-Recognize... About recognition software, it's not problem since I wrote several softwares to recognize iris from still images. The problem is how to setup the hardware system to capture iris in realtime. The system uses "a fixed camera on people passing through a narrow place".

    Actually, I refer to several systems available now. I also did some calculation on sensor type, camera type, Field of View and Depth of View like in this website http://www.dofmaster.com/dofjs.html
    and http://www.tawbaware.com/maxlyons/calc.htm

    What I still consider is about lighting and motion blur. I don't know the difference among NIR, IR and other type of illuminators. As I understand, since capturing face & iris at that distance, low light is very big problem. Which kind of illuminator is suitable for above requirements.

    I know there are many professionals in our forum, could you please consult me on these issues?

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    Re: Camera selection for face and iris capture at a distance

    IR is Infra-Red, NIR is Near Infra-Red. However the majority of cameras have a filter over the sensor to block out any infra-red, so as i said you would need to modify your kit for it to be able to see any IR illumination. There are plenty of people who do this, though i think most do so on cheaper P+S rather than DSLRs which are expensive to make a mistake on. In terms of which type of IR to use, probably not the NIR since as the name implies, it creeps a little into the visible, so a flash of NIR may, depending on exactly what wavelength you use, be visible as a red flash to the subject.

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    Have a guess :)

    Re: Camera selection for face and iris capture at a distance

    If it helps, here's a link to the good folks who do camera IR conversions.

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