Recently, LiDAR technology has become more and more popular with multiple applications and is expected to extend beyond our imagination as it unravels in the future. LiDAR is revolutionizing the world in a variety of ways, from making up the foundation of the new age of automation, sensor applications to 3D printing, 3D scanning, modeling, and smart cities. Let’s take a close look to understand what LiDAR technology is, how it works and some of the main application areas of it.
What is LiDAR technology?
LiDAR, a short for Light Detection & Ranging, is remote sensing technology that utilizes laser pulses, scanners, and specialized GPS receivers to calculate distances and dimensions between the sensor and a given object. This sensor is critical for geospatial technology, autonomous technology, and a variety of other industrial applications. In the case of autonomous vehicles, LiDAR sensors are used to identify and pinpoint the positions of objects such as people, other automobiles, and buildings in relation to the vehicle.
The LiDAR-like technology was first intended for satellite tracking, introduced by the Hughes Aircraft Company, shortly after the invention of the laser. It was initially known as “Colidar,” an abbreviation for “coherent light detecting and ranging,” which was taken from the term “radar,” which was an acronym for “radio detection and range.” All modern laser rangefinders, laser altimeters, and lidar devices are descended from early colidar systems. LiDAR’s first applications were employed by the National Center for Atmospheric Research in meteorology to measure clouds and pollution. With the introduction of GPS in the 1980s, LiDAR became more widely utilized to create 3D models of real-world locations.
How does LiDAR technology work?
LiDAR works on a simple principle: shoot laser light at an object and measure the time it takes for the laser light to return to the LiDAR source.
First the LiDAR system sends pulses of light towards objects (usually ultraviolet or near-infrared). This light reaches the earth surface and reflects off of objects such as cars or buildings. The reflected light energy then returns to the LiDAR sensor where it is recorded. A LiDAR system measures the time it takes for emitted light to travel to the ground and return and from that time calculates distance traveled. The distance traveled is then translated to elevation. These measurements are made using GPS that determines the X,Y,Z position of the light energy and an Inertial Measurement Unit (IMU) that provides the plane’s orientation in the sky.
Given the speed of light (about 186,000 miles per second), the process of determining accurate distance with LiDAR looks to be extremely rapid. The following formula is used by analysts to determine the precise distance of an object:
The distance of the object=(Speed of Light x Time of Flight)/2
Modern LiDAR systems are capable of sending up to 500k pulses per second. The data derived from these pulses are compiled into a point cloud, which is a collection of coordinates objects that the system has sensed. The point cloud is used to generate a 3D model of the environment surrounding the LiDAR.
Types of LiDAR systems?
Based on functionality, LiDAR systems are divided into two types: Airborne LiDAR & Terrestrial LiDAR.
Airborne LiDAR (also airborne laser scanning) is installed on a helicopter or drone for collecting data during flight to create a 3-D point cloud model of the landscape. Airborne LiDAR shoots light towards the ground surface as soon as it is activated, which returns to the sensor immediately after hitting the item, providing a precise measurement of its distance. Airborne LiDAR is further classified into two types: topological LiDAR and bathymetric LiDAR.
Airborne LiDAR technique has supplanted photogrammetry as the most precise and thorough way to create digital elevation models. One significant benefit over photogrammetry is the ability to filter away plant reflections from the point cloud model to build a digital terrain model that includes ground features such as rivers, walkways, cultural heritage monuments, etc that are hidden by trees.
Terrestrial LiDAR systems, as opposed to airborne LiDAR systems, are deployed on moving vehicles or tripods on the earth’s surface to acquire precise data points. These are commonly used for monitoring roadways, analyzing infrastructure, and even gathering point clouds from the interior and outside of buildings. There are two types of terrestrial LiDAR systems: mobile LiDAR and static LiDAR.
Mobile LiDAR is referred to when two or more scanners are attached to a moving vehicle to collect data along a path. This is used in street surveying, when electricity lines, exact bridge heights, neighboring trees, and other factors must all be considered. Instead of taking each of these measures using a tachymeter in the field, a 3D model from a point cloud can be constructed with all of the measurements needed. As long as the model is available, dependable, and has a sufficient degree of precision, this solves the problem of forgetting to take a measurement.
Static LiDAR is the most often used as a survey approach, such as in traditional topography, monitoring, cultural heritage documentation, and forensics. The 3D point clouds obtained from static terrestrial scanners may be matched with digital photos in a relatively short amount of time, especially when compared with other technologies. Each point in the point cloud is assigned a color from the pixel in the picture that was taken in the same spot and direction as the laser beam that generated the point.
What is LiDAR technology used for?
LiDAR technology can be applied in a wide spectrum of industries and the most common is autonomous.
Agriculture & Archaeology, Geology & Oceanography
LiDAR technology is commonly used in agriculture for yield rate analysis, crop scouting, and seed dispersions. Aside from that, it is utilized for campaign planning, mapping under the forest canopy, monitoring insects in the field and other purposes.
Apart from the applications listed above, Archeologists utilize LiDAR to plan field campaigns, mapping features under forest canopy, overview of broad, continuous features indistinguishable from the ground.
In geography, LiDAR can detect subtle topographic features such as river terraces and river channel banks, glacial landforms, measure the land-surface elevation beneath the vegetation canopy, better resolve spatial derivatives of elevation or detect elevation changes between repeat surveys
LiDAR technology is also used to determine the precise depth of the ocean’s surface in order to find any object in the event of a maritime mishap or for research reasons. Aside from finding items, LiDAR is also used to calculate phytoplankton fluorescence and biomass at the ocean’s surface, which is otherwise difficult.
LiDAR with higher resolution systems collect enough detail to identify targets, such as tanks. Examples of military applications of lidar include the Airborne Laser Mine Detection System (ALMDS) for counter-mine warfare by Areté Associates.
Short-range compact spectrometric lidar based on Laser-Induced Fluorescence (LIF) would detect the presence of bio-threats in aerosol form over crucial indoor, semi-enclosed, and outdoor venues such as stadiums, subways, and airports. This near real-time capacity would allow for the quick identification of a bioaerosol leak and the prompt adoption of steps to safeguard occupants and reduce the amount of contamination.
Physics and astronomy
A worldwide network of observatories utilizes lidars to detect the distance to reflectors put on the moon, allowing the moon’s location to be estimated with millimeter precision and general relativity experiments to be performed. Laser altimeters produced global elevation models of Mars, the Moon (Lunar Orbiter Laser Altimeter (LOLA)) Mercury (Mercury Laser Altimeter (MLA)), NEAR–Shoemaker Laser Rangefinder (NLR).
In atmospheric physics, LiDAR is used as a distant detection tool to measure the concentrations of particular elements of the middle and high atmosphere, such as potassium, sodium, or molecular nitrogen and oxygen and from that to calculate temperatures. LiDAR may also be used to assess wind speed and offer information about the vertical distribution of aerosol particles.
Autonomous vehicles and Road construction
The LiDAR sensor’s point cloud output gives the data required by robot software to detect where possible barriers are in the environment and where the robot is in respect to those potential obstacles. In the autonomous spectrum, LiDAR technology has a variety of applications.
Object detection for transportation systems
In transportation systems, LiDAR technology plays an important role in understanding the vehicle and its surroundings, which is critical for ensuring vehicle and passenger safety and developing electronic devices that provide driver assistance. The main advantage of utilizing LiDAR is that the spatial structure is collected, and this data may be merged with other sensors such as radar, etc. to create a clearer image of the vehicle environment in terms of static and dynamic features of the objects present.
Obstacle detection and road environment recognition
Not only does LiDAR focus on object recognition and tracking but it also detects lane markers and road characteristics. It can detect forward items such as automobiles and roadside objects. The data clustering, which also includes the object dimensions, is based on features of each segment based on the object model, which distinguishes different things such as vehicles, signboards.
Reflectors on the back borders of automobiles, for example, are used to distinguish vehicles from other objects. LiDAR reflected intensity data is also utilized for curb detection, with robust regression employed to account for occlusions.
Digital Elevation or Terrain Model
Terrain elevations are critical for building highways, major structures, and bridges. LiDAR technology uses x, y, and z coordinates, making it exceedingly simple to create 3D elevation representations so that interested parties may draw essential conclusions more simply.
As previously stated, LiDAR is a technique that uses laser pulses and sensors to generate a 3D image of the sensor’s surroundings. While it has been utilized since the 1960s, merging LiDAR data with neural networks for autonomous cars is one of the most prevalent use cases today. As LiDAR is transforming the next era of technology and especially AI, it is of utmost importance to understand and prepare for this. TagOn, with a wide range of LiDAR annotation services, will walk you through the whole data input process as well as output validation, which decides a major part of the AI succeeds.
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