Lidar (Light Detection and Ranging) is a remote sensing technology that measures distance to a target by illuminating that target with light. The distance is calculated from the time taken for the light to travel to the target and back to the sensor, using trigonometry. Lidar has applications in topography, meteorology, geology, forestry, geography and cartography, where it is often used to make high-resolution maps. It can also be used as a measurement tool to detect obstacles in robotic or driverless vehicle navigation.