Associated Press “Laser technology reveals lost city around Angkor Wat” http://www.guardian.co.uk/world/2013/jun/18/lasers-lost-city-angkor-wat-cambodia
The technology, known as lidar, works by firing laser pulses from an aircraft to the ground and measuring the distance to create a detailed, three-dimensional map of the area. It is a useful tool for archaeologists because the lasers can penetrate dense vegetation and cover swaths of ground far faster than they could be analysed on foot. Lidar has been used to explore other archaeological sites, such as Stonehenge.
In April 2012, researchers loaded the equipment on to a helicopter, which spent days crisscrossing the dense forests from 800 metres above the ground. A team of Australian and French archaeologists then confirmed the findings with an expedition on foot through the jungle.
Archaeologists had already spent years doing ground research to map a 3.5 sq mile section of the city's downtown area. But the lidar revealed the section was much bigger – at least 14 sq miles – and more heavily populated than once believed.
"The real revelation is to find that the downtown area is densely inhabited, formally-planned and bigger than previously thought," Evans said. "To see the extent of things we missed before has completely changed our understanding of how these cities were structured."
Lindsay Murdoch “The lost city” http://www.theage.com.au/world/the-lost-city-20130614-2o9k7.html