LIDAR

Laser-Based Imagery (LIDAR) is a form of Active Remote Sensing that uses laser lighting to speed and determine distances. Radar guns use this form of technology to determine speed.


The Images shown are created by Laser-Based Imagery (LIDAR). The one shown is the World Trade Center and the area around it; the other shows the same area after 9/11. Coloring is used to show height differences; with Blue representing the highest height and red representing the lowest height. You can see how the highest point changed after 9/11.


http://www.loc.gov/exhibits/911/911-maps.html