Introduction to LiDar Sensors // Self Driving Cars //Autonomous vehicle // Sensor

 

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Lidar — Light Detection and Ranging

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Autonomous vehicle

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Caption Three

What is Lidar
LiDAR, or light detection and ranging, is a popular remote sensing method used for measuring the exact distance of an object on the earth’s surface. Even though it was first used in the 1960s when laser scanners were mounted to aeroplanes, LiDAR didn’t get the popularity it deserved until twenty years later. It was only during the 1980s after the introduction of GPS that it became a popular method for calculating accurate geospatial measurements.
According to the American Geoscience Institute, LiDAR uses a pulsed laser to calculate an object’s variable distances from the earth surface. These light pulses — put together with the information collected by the airborne system — generate accurate 3D information about the earth surface and the target object
Types of LiDAR Systems

• Works during day & night.

• Works in almost all weather conditions except for heavy rainfall and snow.

• Algorithms can be extended from 2D image processing to 3D pointcloud.

• The past Lidars were heavy and were accurate to measure for surveying, Remote sensing. Mounted on airplanes and surveyed for elevations and tree cover.

• Highly accurate, used in geology and digital elevation models (DEMs) for survey purposes.

• Owned by governments or private survey agencies.

• It is Weighed around a ton and came along with highly accurate IMU & GPS.

•  iPad 12 uses lidar for depth estimation instead of multi-camera systems

•  Better foreground-background subtraction. (Better portrait mode)

•  Helpful in post-processing for editing.

•  Build maps using slam technology it can be used by architects and interior designers for planning.

• Large scale mapping for real-estate and developers

• Day & Night surveillance.

• Generating 3D scanned models in 3D copy-paste with aid of 3D printing.

•  LiDar data annotations for objects classification. Semantic segmentation for perception. LiDar based localization for Autonomous vehicles along with GPS & IMU. 

•  LiDar based perception for AD & ADAS.

• Applications for all day & night surveillance using LiDar.

• Multi-view LiDar solution for Scene modelling.

• Research topics: Lidar scan registration, neural network based classification networks.

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 LiDAR and Bathymetric 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, analysing infrastructure or even collecting point clouds from the inside and outside of buildings. Terrestrial LiDAR systems have two types — Mobile LiDAR and Static LiDAR.
How does Lidar work
 An emitter and receiver placed inside the transmitter emits a light beam in near infrared region Light in infrared region are not prone to changes in ambient light.
Why Lidar
Evolution of lidar
The present
Mechanical spinning lidars & Flash lidars with rotating mirrors (MEMS). Used for low-cost surveying in urban environments, autonomous vehicles, drone mapping. It is Bulky, still weighs around 1-1.5kg. Ideal to be mounted on vehicle or drones. It is Still unaffordable for commercial usage.
The Future
Solid-state lidars: No spinning parts, flash lidars.
Lidar applications
Lidar in Autonomous vehicle
 Autonomously driven vehicle doing a cross-country challenge.  Horizontal single layer lidar and vertically placed single layer lidars. Horizontal lidars for getting vehicle centred coordinate and a broader range unlike radar. Vertical lidars for extracting ground plane.
 Autoware: Free and open source software stack for development of autonomous driving development.
LiDar in ADAS Solution
Solid-state lidars in conjunction with camera are explored. For object tracking along with camera. Pedestrian/obstacle detection/classification & tracking during day & night conditions. Development of camera-lidar fusion methods.
Career path & Job opportunities