The approach, known as light detection and ranging scanning (lidar) involves directing a rapid succession of laser pulses at the ground from an aircraft. The time and wavelength of the pulses reflected by the surface are combined with GPS and other data to produce a precise, three-dimensional map of the landscape. Crucially, the technique probes beneath foliage - useful for areas where vegetation is dense. ... The team also found that Angamuco has an unusual layout. Monuments such as pyramids and open plazas are largely concentrated in eight zones around the city's edges, rather being located in one large city...