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Re: [SeattleRobotics] monitor output

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  • Volkan Gungor
    hello, i think for image processing opencv which is a package of c++ could be useful and for capturing image you can use fram grabber cards. i hope that helps
    Message 1 of 6 , Jan 4, 2006
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      hello,

      i think for image processing opencv which is a package
      of c++ could be useful
      and for capturing image you can use fram grabber
      cards.

      i hope that helps




      --- Nate W <delaminator@...> wrote:

      > I hit send a little too soon...
      >
      > On 1/3/06, Nate W <delaminator@...> wrote:
      > > If the goal is to move a series of images from one
      > computer to
      > > another, it would likely be cheaper and easier to
      > connect the
      > > computers with ethernet and send the images as
      > files.
      > >
      > > VGA capture cards exist, but they're not cheap:
      > > http://www.pixelsmart.com/vga.html
      >
      > If you don't need high resolution (about 640x480 or
      > better), you might
      > be able to save money by converting the VGA output
      > from the first
      > computer into a composite video signal (converters
      > are under $100) and
      > then capture the composite signal (lots of options
      > exist for this,
      > less expensive than capturing VGA).
      >
      > > On 1/3/06, Bryan <BNHrobotics@...> wrote:
      > > > I am thinking about attempting a project where I
      > will need to get the
      > > > output from a monitor. I have a laptop with a
      > monitor port that I was
      > > > thinking about using. Does anyone know what I
      > need to do to take the
      > > > data output and do something useful with it?
      > Ideally, I would like to
      > > > be able to do image processing on the output
      > with a second computer.
      > >
      >
      >
      > Visit the SRS Website at
      > http://www.seattlerobotics.org
      > Yahoo! Groups Links
      >
      >
      > SeattleRobotics-unsubscribe@yahoogroups.com
      >
      >
      >
      >
      >
      >




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    • PeterBalch
      ... Why use two computers? I ve been working on a project in which we store and later analyse R/G/B/Sync signals (presumably your portable can produce those).
      Message 2 of 6 , Jan 5, 2006
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        > I would like to
        > be able to do image processing on the output with a second computer.

        Why use two computers?

        I've been working on a project in which we store and later analyse
        R/G/B/Sync signals (presumably your portable can produce those). It turned
        out to be far more difficult that I expected. Most capture cards come with
        s/w to capture N frames to disk. Getting the frames into your program as
        "live" pictures is harder. In our case, it was particularly hard because we
        couldn't afford to lose a single frame and because we had to be able to
        synchronise the frames with other incoming data (to the nearest frame). We
        have yet to find a suitable card. Cards drop frames. There's a variable
        delay between the camera and the input buffer. You probably don't care
        about delays or dropped frames so you can buy a cheaper card.

        My main advice would be to check what driver s/w and program-interface s/w
        the card comes with. What languages do they support? Is there good
        technical support from the company? Windows already has a video-input API.
        Does the card support it? How well? See if there's a user's forum full of
        complaints.

        Another question is: how does their driver s/w buffer the frames? A proper
        frame-queue would be good for us (so if we have to rush off and attend to
        some other matter, we don't lose frames) but we've only come across
        double-buffering. One of the cards we used required a permanent partition
        of memory for it's buffers - so we lost memory even when we weren't running
        our application.

        Compared to getting the data into the computer, analysing it was easy.

        Peter
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