All about automotive lidar

Summary

Here I'll provide a comprehensive overview of automotive lidar technology. Lidar is used for autonomous vehicles and robotics because it's a cool technology. FIGURE 1 Waymo Jaguar I-Pace with several lidars. FIGURE 2 A Chrysler Pacifica Hybrid with 8 Ouster lidars. 1 What lidar does A lidar is a sensor which operates by bouncing light off surrounding surfaces. Lidars typically quantify: distance, by measuring how much time it takes for light to bounce backbearing, by shining the light or pointing the detector in a particular directionreflectivity, by measuring how much light has bounced backspeed, by measuring the Doppler shift in the reflected light.ambient, by measuring the amount of light in the environment in a particular direction FIGURE 3 Ambient, intensity, and range channels of a really old Ouster OS1-64. In general, we are most interested in distance and bearing. Surface reflectivity is also valuable, as it allows detection of road lines in the automotive case. By measuring distance in many directions, an autonomous vehicle can perceive its environment. Each measurement corresponds to a discrete 3D point in space. Through a decade of steady research, engineers designed algorithms capable of leveraging this 3D point cloud to unlock spatial understanding. Obstacle avoidance and precise positioning are just two direct results of this technology. Distance and bearing measurements can be converted into 3D Cartesian points. For example, given range and bearing , , the 3D point is: In contrast, a camera only measures bearing and ambient light intensity. Each pixel of a photo is a measurement of how much light there is in that particular direction. But generally, a camera has much higher bearing resolution than a lidar. FIGURE 4 A point cloud accumulated from an Ouster OS1-64 lidar. 2 Measuring distance Measuring distance is also known as ranging. Basically, it just measures how close something is. There are in general two ways of doing this: Measuring the time som...