Multi-temporal satellite images were used to detect urban
expansion in Beijing from 1972 to 2010 (Table 2). The data from
1972 were Corona (KH-4B) panchromatic images that were taken
by the Central Intelligence Agency (CIA) and the U.S. Air Force and
declassified on February 24, 1995 (Dashora, Lohani, & Malik, 2007).