LIDAR

http://www.noaanews.noaa.gov/stories/s798b.htm

The LIDAR is a remotes sensing technology that measures distance by illuminating a target with a laser and evaluating the light that reflects back. This particular image is of ground zero on September 27, 2001 a few weeks after the 9/11 terrorist attacks. This technology was useful in the situation because regular images were cloudy from the debris and because there was so many little pieces everywhere it was hard to see the actual level of what still existed. This image clearly shows what was left from all the destruction and what surrounding buildings survived the attacks.