LIDAR

Light Detection And Ranging, or LIDAR, is an visual remote sensing technology that can calculate the distance to, or other properties of a target by revealing the target with light, often using a laser. They are used to scan buildings, mountains and even roads. This image  is of a New York City after the 9/11 attacks.
Height data from LIDAR measurements can be shown visually like this.

http://rst.gsfc.nasa.gov/Sect8/Sect8_8.html