LIDAR

http://imaging.geocomm.com/gallery/
LIDAR, also known as Light Detection and Ranging (or LADAR, but that is primary for military purposes), is an optical remote sensing technology. It measures properties of a target (i.e., the distance to that target) by illuminating the target with light (ultraviolet, visible, or near infrared light), often using pulses from a laser. LIDAR technology has many uses: archaeology, geography, geology, seismology, forestry, and atmospheric physics. LIDARS are particularly used for geographical-related purposes in the following instance: LIDAR can detect subtle topographic features, like river terraces, and measure land surface elevation.
The LIDAR map above shows Ground Zero in NYC, rendered on September 27th of 2001.