What is LiDAR? Important Things You Should Know About It
Given the numerous fields where it is used, there is no better time to learn about LiDAR definition, types and applications than today. Light Detection and Ranging (LiDAR) is a well-known surveying method where special laser sensors equipped with light waves are used for measuring the distance of nearby obstacles and objects.
LiDAR was first used in the 1960’s when the laser scanners were mounted to planes. However, it became a popular tool for providing accurate geospatial measurements only after the introduction of the GPS in the 1980’s.
The LiDAR technology illuminates the target object with pulsed light and then measures the reflected pulses using a sensor. The fluctuation in the laser return wavelengths and times are then used for making the digital 3D representation of the target object.
How Does LiDAR Work?
Just like radar uses radio waves and Sonar uses sound waves, LiDAR uses light waves from a laser to detect objects. The LiDAR system takes into account the total duration that the light takes to hit the target object and reflect back to the scanner. Once this happens, the system calculates the total distance with the help of the velocity of light. This process is also called the “Time of Flight” measurement.
Today’s LiDAR systems are powerful enough to fire up to 500,000 pulses every second comfortably. All of these pulse returns are then put into a “point cloud”. This is a collection of data points that are usually defined by a specific coordinates system and used for creating 3D meshes. These 3D meshes play a vital role in 3D modelling for different fields, such as architecture, construction, medical imaging, manufacturing, 3D printing and other virtual reality applications.
Different Components of the LiDAR System
There are multiple components that make the LiDAR system very powerful and effective and make data generation, recording and geo-referencing quite hassle-free. These components include:
- Scanner & Optics
- Photodetector & Receiver Electronics
- GPS (Global Positioning System) & IMU (Inertial Measurement Unit)
Each of these components plays a critical role in the LiDAR process and makes it incredibly easy for researchers to obtain needed data in the most accurate way possible. So, learn about all these components along with an appropriate LiDAR definition for maximum benefits.
Types of LiDAR Systems
Below are the two primary types of LiDAR systems based on the functionality you may use for your project.
1. Airborne LiDAR
This type of LiDAR system is installed on top of the drone or helicopter. It emits lights toward the ground, which returns to the sensor. It’s further divided into two types — Bathymetric and Topographic LiDAR.
Bathymetric LiDAR: These types of LiDARs are mainly used for measuring the depth and elevation of water bodies. As part of the bathymetric LiDAR process, the infrared light goes back to the aircraft, helicopter or drone from the water surface while the additional green laser light goes through the water and measures its exact depth.
It’s quite useful and has a great significance near coastlines, shores, river boundaries and in harbors. It’s also used from time to time to locate objects on the ocean floor.
Topographic LiDAR: It’s used for obtaining the surface models that play a vital role in many applications, such as urban planning, forestry, landscape ecology, geomorphology, survey assessment as well as coastal engineering.
2. Terrestrial LiDAR:
Terrestrial LiDAR systems can be installed on a moving vehicle or tripod for collecting highly accurate data points. Terrestrial LiDAR has two types and plays a vital role in creating 3D modelling and surveying projects.
Mobile LiDAR: Mobile LiDAR systems comprise of the camera, sensors, INS (Inertial Navigation System) and GPS, are used for observing roads and analyzing infrastructure. They can be mounted on trains, vehicles or even ships.
Static LiDAR: The static LiDAR system is used for collecting LiDAR point clouds from a fixed location. As part of this system, a portable ranging and the laser-based imaging sensor is installed on a tripod. This sensor collects point clouds from the exterior as well as inside of the building.
Some of the most common applications of the static LiDAR system are into mining, engineering, surveying and archaeology.
Applications of LiDAR Technology
LiDAR technology makes it incredibly easy to collect crucial data points in remote areas and use them for various short-term and long-term developmental objectives. Mentioned below are some of its major applications.
From time to time, LiDAR technology is used for measuring the depth of the ocean as well as calculating biomass and phytoplankton fluorescence in the ocean surface. Usually, the process is very tough and time-consuming, but LiDAR makes everything easy and hassle-free.
Agriculture & Archaeology:
Along with analysing the yield rates on agriculture fields, LiDAR technology is used for a range of other objectives like fertiliser and seed dispersions and crop scouting.
LiDAR empowers researchers to create a topological map of the fields and highlight sun exposure & various slopes, thereby making it easier to determine where to apply fertiliser for maximum production.
Digital Elevation Model (Also known as Digital Terrain Model or DTM)
It has many applications in archaeology as well, such as mapping features under the forest canopy, field campaign planning, etc. LiDAR produces high-resolution datasets at a swift pace and ensures that the information used for the field analysis is 100% accurate.
LiDAR technology has x, y, and z coordinates, and can quickly produce the 3D representation of terrain elevations that are found on earth’s surface. They are used for capturing the width, length and height of the surface while constructing bridges, buildings, roads, etc.
The high quality and data-rich digital elevation maps generated by the airborne LiDAR help researchers in unearthing various geomorphology (that branch of geoscience that talks about the origin and development of earth’s surface) related secrets.
With the help of these maps, researchers can easily detect faults — the discontinuity in a rock’s volume — and measure uplifts.
Military personals of various countries use LiDAR to get insights about the border surrounding land, spot suspicious activities/objects, and create high-resolution maps of remote locations. Since these operations directly affect the national security, LiDAR technology’s role is extremely important here.
The green light laser used in the LiDAR technology plays an important role for collecting underwater information like river’s flow strength, width, depth, etc., which is further utilized to create a 3D river model and flood fringe map.
Other applications of LiDAR are in the fields of autonomous vehicles, biology & conservation, atmosphere, mining, astronomy, robotics, spaceflight, transport, and wind farm optimization.
Whether you’re heading a government department or are part of an organisation that uses LiDAR technology, make sure you learn to use it efficiently. An ideal way of doing so is to opt for TopoDOT and automate the entire process.