Satellites, Balloons, and Math used to Count Inauguration Crowd

From CNET News.com:

U.S. President Barack Obama was sworn in on Tuesday in Washington. But the number of people who braved the frigid D.C. weather to watch the historic event could have been anywhere between 800,000 and 3 million, depending on who you talk to. Researchers have projected widely varying figures for the event's attendance, based on satellites circling above the clouds, aerostat balloons tethered blocks away, television coverage of the crowd, and good old-fashioned mathematics calculations. Steve Doig, a journalism professor at Arizona State University who specializes in crowd counting, said he is estimating there were 800,000 people in attendance, based on a satellite image taken by GeoEye about 40 minutes before the swearing-in ceremony.

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