What is LiDAR, How it Works and How it's Being Used in 2021
March 17 2021
LiDAR, which stands for Light Detection and Ranging, is a remote-sensing technology that uses a laser beam to get information about surrounding objects.
Since its inception, scientists have used LiDAR to map the earth’s surface and acquire meteorological data. It sounds complex and let's be honest, the the technology rarely is affordable but their use in geospatial industry has great return on its investment (but at a cost).
But tech gets more accessible with the years. Now that the cost of LiDAR sensors has dropped, this technology is increasingly used on consumer devices such as self-driving cars, augmented reality gadgets, smartphones, and even vacuum cleaners.
In this article we’ll talk about how LiDAR works and cover some of its most popular and useful applications in 2021.
How Does LiDAR Work?
Systems that use LiDAR send out pulses of light just outside the visible spectrum and measure how long it takes for each pulse to return. Whenever the pulse reaches some object, data points are collected regarding its direction and distance from LiDAR.
Using LiDAR sensors, one can determine the shape and orientation of any object in space based on the time difference between the emission of a laser signal and its return to the sensor after bouncing off.
With repeated pings, a device with LiDAR can also learn how nearby objects move, their speed, and whether they are facing toward or away from the LiDAR device.
There are three main components of any LIDAR device:
- a laser,
- a scanner,
- and a specialized GPS receiver
Systems that use LiDAR send out pulses of light just outside the visible spectrum and measure how long it takes each pulse to return. Whenever the pulse reaches something, data points are collected regarding its direction and distance.
The LiDAR instrument emits rapid laser signals, sometimes up to 150,000 pulses per second. Although every device might work differently, generally, they send out beams by sweeping in a circle like a RADAR dish while also moving a laser up and down.
Here’s a process that every LIDAR device follows:
- A laser emits signals
- A signal reaches an obstacle
- A signal reflects off the obstacle
- Signals return to the receiver
- Laser pulses are registered
- Each registered pulse is assigned a location and representation in a LiDAR point cloud
In most cases, a point cloud works as a middleman between raw data collected by LiDAR processes and 3D models. Yet clouds can be used to store any spatial information and manipulate it for various algorithms, artificial intelligence, machine learning, and other analysis software. For instance, a LIDAR mapping program can geo-reference each point in a point cloud to create highly-detailed maps of real-world environments.
Wavelengths of LiDAR sensors range from the infrared (10 micrometers) to the ultraviolet (250 nanometers) and can be applied to a variety of substances, including rocks, rain, chemicals, air, clouds, and even single molecules. For example, the optimum combination of wavelengths can allow for the remote mapping of atmospheric contents by detecting wavelength-dependent changes in the returned signal intensity
A laser beam that is narrow and focused can map features at very high resolutions; for example, an aircraft can map terrain at 30-centimetre (12-in) resolution.
As opposed to a direct reflection one may find with a mirror, LIDAR light is often reflected through backscattering — a phenomenon that occurs when light particles are scattered at angles to the original direction of motion .In different LIDAR applications, different types of scattering are used: primarily Rayleigh scattering, Mie scattering, Raman scattering and fluorescence.
There are two main classification or types of LiDAR systems:
- Terrestrial LIDAR operations happen on the Earth's surface and can either be stationary or mobile.
- Airborne LIDAR system is a technology in which a laser scanner, attached to an aircraft, such as helicopters, airplanes, or a drone, creates a 3D point cloud map of the landscape.
Airborne system LIDAR is currently the most detailed and accurate method of creating digital elevation models, replacing photogrammetry.
LIDAR vs RADAR: The Key Difference
You may think that the LIDAR technology is much alike RADAR, right?
While their basic purpose is the same – detecting distant objects – it is essential to recognize the differences between LiDAR and RADAR.
The RADAR system works in much the same way as a LiDAR, except the RADAR system uses radio waves instead of lasers. Following the same logic, you'd say that SONAR uses sound waves, right? You would be correct.
In contrast to light waves, radio waves have much less absorption when bumping against objects. Therefore, they can work over relatively long distances and through fog or clouds.
That’s why RADAR is commonly used by the military, where planes and battleships feature RADAR to measure altitude and detect other transport devices. The system is also used by anti-collision systems on aircraft, by air traffic controllers, or in radar astronomy.
LiDAR, as previously mentioned, is a light-based remote sensing technology. As light waves have a shorter wavelength than radio waves, they are more accurate in painting a detailed picture of the target.
A regular RADAR system, for example, has a resolution of several meters at a 100 meter time interval, while LiDAR systems have a resolution of a few centimeters at the same distance.
In addition to that, LiDAR doesn't just measure distance, but also infer a lot of extra information about the shape of the object, too. Because of this, LiDAR is used in laser altimetry, contour mapping, and digital terrain models.
Interesting fact: Several automakers, including Google, Uber, and Toyota rely heavily on LiDAR systems to navigate their vehicles, whereas Tesla self-driving cars rely on RADAR technology as their primary sensor.
We've covered what LIDAR is and how it works. Let's see how LIDAR is being used in today's innovative world.
Apple Added LiDAR to iPhone and iPad: What Now?
But why adding LIDAR sensors could be the next big thing for the smartphone industry? Why would Apple do something like that? Is this some sort of genius masterplan that will come with the "rumored" Apple AR headset.
Following are some of the most common ways in which LIDAR could be used in the Apple devices, both now and in the future.
Measure is an app included on Apple's iPhone and iPad which can serve as a virtual substitute for a ruler, level, and tape measure.
Built-in LiDAR allows you to measure the distance between two points, find out objects’ measurements , and even check if the surface is straight.
In addition to that you can impress your friends by measuring their height:
(Source) You can use the shutter button to take a photo of a person with their height measurement.
In addition, you can get a history of all of your measurements and do more granular measurements with the Ruler View.
LiDAR technology greatly enhanced Apple's AR capabilities, particularly when it comes to scanning real-world environments and displaying virtual objects within them.
Another advantage of lidar sensors is that virtual objects stay in the same spot regardless of where you are in the room.
Later, you can refine, smooth, or simplify the scan. You can measure the distance between any two points in the scan and share it in different formats.
When used with Apple devices, LIDAR enhances the quality of footage, especially in challenging scenarios.
In low-light scenes, the LiDAR sensor allows for a focus time of 6 times faster for both video and photo sessions. Are photo/video abilities important on smartphones? Does the bear poop in the woods? (Aggressive yes is the answer to both rhetorical questions.)
LiDAR enhances night mode quality by providing precise distance measurements. It also helps to calculate the amount of bokeh to add, which improves the sense of artificial depth.
The iPhone's camera utilizes computational photography to obtain a balance between foreground and background exposure even when the contrast is extreme like it is here.
As Apple shares, LiDAR offers "the ability to measure light distance and use pixel depth information of a scene,"which enhances every step of the photo and video capturing process.
Augmented Reality Games and Apps
Finally, huh? Basically any AR application could benefit from adding LiDAR.
Objects in games can be placed more accurately within a real-world environment. With LiDAR scan, AR apps now finally recognize what should be in front of a virtual object or behind it. The positioning of objects doesn’t depend on where you stand, allowing for more fluid gaming and other experiences.
The Playground AR: Physics Sandbox (4.7 rating app on App Store) app, for instance, lets you place virtual blocks in a real-world environment to see how they interact with one another.
The game lets you use cubes, rectangles, triangles, cylinders, cue balls, and model cars, then place them on a floor, table, or other surface.
You can arrange and move cubes however you want, and they will interact realistically with your environment.
In Hot Lava, another cool AR game, the LIDAR scanner proves its capabilities even further. Do you remember playing floor is lava as a kid? Congratulations on having an awesome childhood!
After scanning a living room with an iPad, this app generates hot lava and platforms for a virtual character to leap on for augmented reality.
LiDAR makes augmented reality applications more immersive than ever before. This, undoubtedly, will impact entertainment as well as business applications that use LIDAR to its full possibility.
Apple is expected to employ LIDAR technology even more with their upcoming AR glasses project.
But it's not just Apple that makes full use of laser scanning technology.
Let’s take a look at how LIDAR is enhancing existing workflows and opening incredible opportunities for new industries.
9 Hottest and Most Practical Applications of LIDAR Technology In The Real World
Growing numbers of robots utilize LiDAR for obstacle avoidance and navigation, both in consumer-facing markets and scientific mediums.
P.S.: If you're looking to build your own LiDAR digital robot in Unity, check out Nakisa's LiDAR workshop.
Wyze and Roborock, for example, have developed vacuums that recognize objects (a table leg from your shoes) to better navigate around them.
The Boston Dynamics video below demonstrates how LiDAR has found its way into more advanced robots such as Spot:
(Source: YouTube video)
Looks super cool right (and also give you some hibbie jibbies if you watched "Metalhead" episode of Black Mirror.)
In addition to the LiDAR system in its head, the robot uses an optical scanner and a camera to read QR codes.
Meteorology & Atmospheric Studies
With LiDAR technology, many different measurements can be made, such as profiling clouds, studying wind patterns, studying aerosols, and quantifying different atmospheric components.
In turn, atmospheric components can provide useful information about surface pressure, greenhouse gas emissions, and humidity.
The ground-based LiDAR, for example, can detect cloud boundaries by operating in near infrared and visible bands.
It has already been mentioned that LiDAR technology is becoming increasingly mainstream in self-driving vehicles as it is far more accurate than cameras or RADAR at judging distance and impervious to surfaces that are reflective, textured, or textureless.
A large part of LiDAR spike in popularity can also be attributed to the decline in laser sensor prices.
For the first time, Google offered a driverless car prototype in 2012 using a US$70,000 LiDAR. By 2017, Waymo announced that its LiDARs were 90% less expensive. Today, Luminar offers LiDARs designed for autonomous driving for under US$1,000.
Renewable energy sector is now beginning to successfully employ Doppler lidar systems to measure wind speed, turbulence, wind direction, and wind shear.
The UK's Carbon Trust energy consulting company used floating LiDAR systems to compare measurements of wind speed and direction with existing offshore masts.
Their study found that LIDAR measurement systems are not only more accurate, but can also lead to 90% savings during installation and maintenance, compared to traditional met mast solutions.
Space exploration & landing
LiDAR has been identified by NASA as a promising technology that will enable autonomous precision safe landing of future robotic and crewed lunar vehicles.
LiDAR technology can provide three-dimensional terrain elevation maps, high precision distances to the ground, and approach velocity necessary to land robotic and manned vehicles with greater precision.
As of now, NASA is testing new flash LiDAR systems aimed at meeting the needs of future planetary landings.
Agriculture technology companies can use LiDAR to identify areas with optimal sunlight for crop growth.
Machine learning systems can also be trained to identify crops that require vegetation, water and fertilizer.
Oil and gas exploration
Due to its shorter wavelength, LiDAR can detect tiny molecules in the atmosphere.
That’s why a new method called Differential Absorption LiDAR (DAL) is being used for locating new oil and gas deposits.
Laser metrology of seafloor takes only 2.5 hours, while traditional methods such as acoustic or LBL/Inertial mixed measurements take nine to twelve hours per measurement. In addition to that traditional systems are using more expensive equipment and provide less visual information.
Tsunami modeling & Landline (natural catastrophe analysis)
LiDAR is used by tsunami warning systems to warn people in their area if a tsunami is approaching.
A LiDAR also measures the elevation of a seashore and underwater. This information can be used to feed the LiDAR data into a GIS, which is used to predict which areas may be affected by tsunami the most.
(Source) Flooding from Hurricane Isaac was mapped using LiDAR.
In addition to that aerial LIDAR systems can be used to obtain accurate regional landslide information at a faster rate, improving safety and response times.
Forensics and Fingerprints
LiDAR is highly useful for building detailed evidence quickly, acquiring thousands of measurements per second.
Because forensic investigations always begin by acquiring, reviewing, and analyzing evidence, LIDAR-based tools can help forensic investigators make the data collection process quicker and more accurate compared to manual approach.
For example, a traditional method for fingerprint detection uses chemical reagents, such as ninhydrin or diazafluorenone. Infrared lasers and 3D scanning allow for capturing fingerprints without a chemical solution.
In the future, LiDAR scanners might replace dusting entirely, as they can make accurate fingerprint scans in seconds.
Within the next several years LiDAR will become an integral part of many innovative industries, including augmented reality. If there's someone like Apple who is distributing millions of LiDAR-equipped devices in forms of smartphones and tablets, than it's safe to say there will be more LiDAR (and AR) apps out there.
Heck, you might create the next big one...
Do you want to take your AR development skills to the next level (yes, you can learn about LiDAR app development too) and learn to make the most out of LiDAR tech in your iPhone?
Check out our free workshops we did about LiDAR tech and it's development using Unity:
- LiDAR Sensors and the Future of Mobile AR Development w/ Jerry Medeiros
- Build and Control Your Own LiDAR Robot w/ Nakisa Donnelly
Both are accessible if you fill in the form.
Looking to learn more about XR development?
If you're serious about becoming a professional AR/VR developer/designer, download our 10-week XR Development with Unity syllabus.
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