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Counting Crowds
Million Man March

We first learned of Farouk El-Baz's method for counting large congregation of people from the wonderful Crowds project at the Stanford Humanities Lab. In the Gallery section, click the third thumbnail image in the first column. A quick Googling returned this article from Wired in which El-Baz lays out his methodology. Adopted from those used to count dunes in a desert and trees in a forest, it goes like so:

1. Fly over the crowd at peak times using a fixed-wing aircraft. (Shaky helicopter platforms blur photos, increasing the effort required to analyze them.) Altitude should be 2,000 feet or less.

2. Photograph the area in strips using a digital camera, with 60 percent overlap between successive pictures to allow stereoscopic viewing (helpful for making ambiguous pictures clearer). Image resolution should be about 1 foot per pixel.

3. Load the photos in an image-processing program and co-register them with a 1-meter-resolution US Geological Survey orthophotomap - a perspective-corrected collage of aerial shots of the area with a uniform scale.

4. Superimpose a grid on the image and classify its units by the apparent density of people per unit.

5. Place a cross or dot on each individual head or shadow point.

6. Count or, if necessary, estimate the number of people in each grid unit, then tally the numbers.

7. Calculate error - basically the number of grid units divided by the degree of uncertainty about how many people they contain.

Million Man March

Bosque del Apache National Wildlife Refuge

Farouk El-Baz was asked by ABC News to estimate the number of participants in the Million Man March in Washington, D.C., in 1995. The Nation of Islam, which organized the event, estimated attendance at around 1.5 million. The National Park Service, however, reported a peak attendance of 400,000. Controversy naturally followed:

When crowds gather to make political statements, it matters how many people turn out. Crowd size matters to organizers, who invariably say they made their point. It matters to police departments, who insist they fielded the right number of officers. It matters to the media, who often claim they've reported the facts. And it matters to elected officials, who often like to act as if the whole thing never happened.

Who had the largest rally and therefore are the true barometer of public opinion? Anti-war or pro-war supporters? Pro-choice or pro-life supporters? Depose the king or let him reign on? Exile the dictator or burn him in the public square?

The controversy was somewhat resolved when Farouk El-Baz's analysis produced an estimate of 870,000 with a margin of error of about 25 percent. This meant the crowd could have been as high as 1.1 million. Both the National Park Service and the Nation of Islam found this acceptable.

Sokol Congress at Prague

And then it occurred to us: what if the size of the crowd were twice as large as the estimates? What if there were 5 million people or even 10 million? Would the National Mall have coped? How about 150 million anti-war protesters, half the population of the United States? Would L'Enfent's Washington have been able to cope with that many people and survive? Is there a designed landscape that could? Haussman's Paris? Sixtus V's Rome?

Could Chicago's Millennium Park cope with the 1.5 million+ that usually descend to the lakefront for the 4th of July fireworks?

We ask this because when it comes to the generative potential of the crowd in design, it seems that landscape architecture tends to exhibit an engineering or even an architectural mentality. Don't ask us for examples. Let's pretend for now. But think of garden walls, iron fences, hedge rows, bollards, concrete pavers, 10,000 max outdoor seating capacity, tunnels, bridges. By their nature, inflexible.

(Un)fortunately, landscape is anything but rigid.


So introducing the Mimosa-Hedge©. Normally, on a quiet weekday afternoon, it provides the necessary edge condition, regulates foot traffic, or screens sound, visual, and possibly even environmental pollution. But during the 4th of July with its attendant hundreds of thousands of revelers, the Mimosa-Hedge© fluctuates between a solid wall, a permeable membrane and a borderless border. When it senses the presence of a large crowd, it responds by contracting parts of its shruberry thicket to create openings, allowing for freer circulation within the space. Or entirely collapse, uniting previously distinct spaces into a larger, more accommodating one. Later, when the crowd dissipates, it starts to unfurl, unharmed, resuming its normal duties.


And the Fractal-Beach©. Rather than retracting when the crowd multiplies exponentially, it sprouts additional beach territory out into the ocean and defoliates when the crowd departs. In seconds.


And the Prunnel©. As a fundamental condition of their materiality, steel and concrete expand and contract, but these physical events are muffled in architecture and civil engineering. Not Prunnel©. It can response to increases in humidity and heat emitted by the crowd by inflating, and does so exponentially beyond what physics allows. So no more catastrophic deaths of pilgrims during the Hajj. A full-scale evacuation of Manhattan preceding the arrival of a tsunami will go fast and orderly. Whether informed and formed by weather, mass hysteria or political instabilities, the Prunnel© exploits them all.

Jamarat Bridge

We have other patents, but those are for future posts.

But who will fund these projects, you ask? Multi-billionaire Dubai sheiks, of course.

Meanwhile, returning to the first link, check out the other stuff in the Gallery section, such as The Crowd in Cinema, Contagion, and The Moscow Metropolitan.

POSTSCRIPT #1: Zombie Infection Simulation.

POSTSCRIPT #2: Evacuating Manhattan.

POSTSCRIPT #3: Farouk El-Baz is director of the Center for Remote Sensing, Boston University.

Farouk El-Baz, “The [?]-Man March.” Wired (June 2003).

  • Unknown
  • December 11, 2011 at 6:59:00 PM CST
  • Hi!
    Can you estimate this crowd at the Moscow rally on Saturday?

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