Re: Empirical crowd estimates

From: spike66 (spike66@attbi.com)
Date: Sat Feb 22 2003 - 15:01:18 MST

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    I reply to my own post with a better idea.

    spike66 wrote:
    > Anders Sandberg wrote:
    >
    >> It is somewhat related to the algorithms used in ant tracking I sent a
    >> few weeks back to Spike, although this does apparently scale better.
    >
    > I propose a test where we get about a
    > thousand volunteers, have them stand on an area the
    > size of a football field, take a radar image, then
    > get them to stand between the 20s, take another image,
    > bring them inside the 40s, at which time it would be
    > about as densely packed as any crowd ever gets, take
    > an image... Then from that, we could compare radar images of a
    > rally, create a crowd density contour map with
    > iso-humes... spike

    It occurred to me that we already have such crowd
    images from which we could make a darn good estimate
    of crowd density. At the annual Bay to Breakers 10k,
    there are webcams all along the route. Since many of
    the participants wear wacky costumes, it would be easy
    to track the progress of any given individual. (We might
    even recruit free assistants and the local high school:
    here guys, track this nude blonde in these billion digital
    images.)

     From the speed of an individual approximates the crowd
    flow rate. We can get accurate numbers of participants
    at the finish line where a row of cameras take souvenier
    photos every second. We have the total number of
    participants, a flow rate and a width, since we know
    the distance from sidewalk to sidewalk. From that, a
    simple calculation gives crowd density.

    Take a radar image of that, compare to radar images at
    the rally or peace march and we are there.

    spike



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