Tea Party Express Tax Day Rally
Tea Party Express Tax Day Rally on the National Mall, April 15th, 2010
This photograph of the Tea Party Express Tax Day Rally in 2010 is an excellent example of a classic crowd count. The aerial balloon image clearly shows a good view of the entire crowd gathered at the event. For the analysis of this event, DDIS used a traditional two-dimensional overlay grid. DDIS chose a 2D overlay strategy due to the size of the crowd, which allowed it to be counted entirely by hand. The yellow dots represent each person as they were hand-tallied using a mechanical counter. Small squares divide up discrete clusters of people while larger color-coded grids are used in less dense open areas.