LiDAR, or Light Detection And Ranging, is a technology used to map the surrounding world using the reflection characteristics of invisible light emitted by infrared lasers. Since the invention of the infrared laser in 1960, LiDAR has been useful in thousands of modern applications.
Since LiDAR’s invention, and later with the advent of GPS, its most conventional application has been mapping the topography of Earth’s surface and the sea floor through topographic and bathymetric LiDAR. With the accuracy, precision, and flexibility of LiDAR, scientists can use it to make more accurate shoreline maps, create elevation models, and even assist in emergency response operations.
Most topographic LiDAR systems are mounted to the underside of airplanes. The laser emits pulses of near-infrared light at a rate of about 400,000 times a second and the reflection of this light from the surface of the Earth is detected via sensors. A simple mathematical formula can be used to determine the distance between the sensor and Earth while the position is recorded via GPS.
d = c ∙ t ÷ 2
In this equation, “d” is the distance between the sensor and the ground, “c” is the speed of light in Earth’s atmosphere, and “t” is the time between the laser being emitted, reflected, and then detected by the sensor. The formula is simple and incredibly effective, as the most advanced of these airborne systems are accurate to within 6 inches of true elevation.
History
The invention of the infrared laser did not make LiDAR possible, rather it made it much more feasible. In the 1930s, the reflection of visible light from searchlights was used to measure the elevation and density of clouds. The use of infrared lasers instead of visible light made these measurement techniques much more practical and precise. From 1971 to 1972, NASA even used LiDAR onboard the Apollo 15, 16 and 17 capsules to map the surface of the moon.
LiDAR continues to be a powerful topographical tool that is used in many applications including forestry, hydrology, urban planning, costal engineering and more. However, LiDAR's is much more than just a topographical tool and it is currently being utilized in many other use cases.
Applications
In recent years, LiDAR has rapidly evolved, with new uses in growing technology spaces including augmented reality, autonomous vehicles, factory logistics, and mobile robotics.
Similar to how topographical LiDAR is used to map the surface of the Earth, the reflection of non-visible light in confined spaces can be used to effectively generate a three dimensional map of the immediate surroundings. This is useful for augmented reality where the LiDAR helps identify whether a space is open, confined, or if obstacles are in the way, allowing the technology to superimpose computer generated images onto the user's view in real time. Users can interact with imaginary objects, write in open space, or perform any number of tasks, all while such assets appear anchored in place in the area around them.
In order to provide an accurate picture of 3D space, the infrared laser is typically supplemented by a rotating mirror. In this way, the laser is reflected around its immediate surroundings in a 360° area. This application is incredibly useful for preventing accidents in autonomous vehicles because the LiDAR is able to paint an accurate picture of objects moving in the vehicle’s vicinity. This technology is so valuable that Israeli company Innoviz was recently awarded a $4 billion dollar contract to exclusively provide Volkswagen with LiDAR for their anticipated autonomous vehicles.
LiDAR is used for similar purposes in mobile robotics, most commonly for factory logistics. Autonomous Mobile Robots (see Dura Digital’s blog “Building the Future: an Overview of AMR”) commonly use LiDAR because they work in incredibly dynamic and frequently congested environments, oftentimes alongside humans. As a result, spatial awareness is crucial for the roles they are trusted to perform making LiDAR a perfect technology to utilize.
The Dura Digital Takeaway
LiDAR is an incredibly useful tool for the continuously evolving robotics and technology industries. Some major players in the technology space, such as Elon Musk, are not exactly optimistic for LiDAR’s use in the long-term. He contends that “Computer Vision” technologies through cameras and conventional radar are more than capable of facilitating autonomous navigation. Nevertheless, LiDAR remains a relatively cheap and readily accessible technology for applications that require mapping the surrounding world.
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