Lidar

LiDAR stands for Light Detection and Ranging. It uses a pulsed laser to calculate an object’s variable distances from the earth’s surface. These light pulses generate accurate 3D information about the earth surface and the target object. It can get a sense of both the physical dimensions and motion (if any) of objects in its vicinity. method for calculating accurate geospatial measurements.

There are three primary components of a LiDAR instrument — the scanner, laser and GPS receiver. Other elements that play a vital role in the data collection and analysis are the photodetector and optics. Most government and private organizations use helicopters, drones and airplanes for acquiring LiDAR data. The technology is becoming widespread and is included on the new iPhone 12 smartphones.

How Lidar Works

Lidar functions by pointing a pulsing laser at a targeted area which then reflects the surface it encounters. A sensor uses the time it took for each pulse to return to the sensor to calculate the distance it traveled. The Laser ranges are combined with positional and orientation data gathered through integrated Inertial measurement unit and GPS to create a Point Cloud.

Each point in the cloud has 3D spatial coordinates (latitude, longitude, and height) that correspond to a particular origination point on the earth.

Types of LiDAR Systems

LiDAR systems are divided into two types based on its functionality — Airborne LiDAR & Terrestrial LiDAR.

Airborne LiDAR

Airborne LiDAR is installed on a helicopter or drone for collecting data. As soon as it’s activated, Airborne LiDAR emits light towards the ground surface, which returns to the sensor immediately after hitting the object, giving an exact measurement of its distance. Airborne LiDAR is further divided into two types — Topological (land) LiDAR and Bathymetric (under water) LiDAR.

Terrestrial LiDAR

Unlike Airborne, Terrestrial LiDAR systems are installed on moving vehicles or tripods on the earth surface for collecting accurate data points. These are quite common for observing highways, analyzing infrastructure or even collecting point clouds from the inside and outside of buildings. Terrestrial LiDAR systems have two types — Mobile LiDAR and Static LiDAR.

The image below shows how static lidar can be utilized indoors to track the number of people and their movement patterns indoors. The insights gained can be used by public safety, sales and marketing and logistics executives to improve their operations.

LiDAR in autonomous vehicles

LiDAR should be called the eye of an autonomous vehicle as it looks at the surroundings of the vehicle, calculates distance, identifies obstructions ahead, illuminates objects with a laser and then creates a high-resolution digital image. LiDAR is also used to avoid collisions by measuring the distance between a car and any other car in front of it. This is done by mounting a LiDAR on the bumper or the roof. The Adaptive Cruise Control system in an autonomous car gets the information from the LiDAR sensors, using which it decides when to apply the brakes, slow down or accelerate.