The technology of LiDAR or "Light Detection and Ranging" represents a complete turning point in drone surveying. Its capability to process high-resolution 3D data with precision can be utilized across various industries. For example, in forestry, this technology aids in assessing the density of trees and monitoring forest conditions. It's also used in urban planning and infrastructure inspection, mining standards evaluation, stockpile volume calculation, archaeological site exploration, and much more.
In this article, Aonic will guide you through the basic information about LiDAR technology along with the methods of processing Point Cloud data in order to create accurate 3D maps.
Light Detection and Ranging, or LiDAR, is a remote sensing method that utilizes laser energy to measure the distance between a sensor and ground objects. The emitted energy hits the objects and reflects back to the sensor, allowing us to calculate and analyze the time it takes for the laser energy to be reflected. As a result, we can create an accurate 3D representation of the terrain and the objects situated below it.
LiDAR is classified as an "Active Sensor", meaning that it can generate light energy on its own without depending on sunlight to reflect energy back to the sensor. This allows it to be used in areas not reached by sunlight and during nighttime hours.
Typically, there are several types of LiDAR sensors, which differ based on their application. In some cases, they may be installed at a base station or mounted on vehicles. The operational principles of the technology remain the same, but they vary in the method of collecting data, whether it comes from the ground or from above.
Mounting LiDAR sensors on drones, such as the DJI Matrice 350 RTK and Mavic 3 Enterprise, is another popular method today. This is because drones can effectively cover a large area and provide high-precision three-dimensional coordinates. This efficiency is achieved through the use of GNSS receivers (High Precision RTK for Surveying Drones) and high-resolution drone cameras. Once the data is collected, it must then be converted from electrical signals into three-dimensional coordinates by combining information from the IMU and GNSS with various software.
The capability to gather data through obstacles is due to the properties of certain materials that reflect some light while allowing other light to pass through, such as in areas covered by vegetation, for example, in rubber plantations or dense forests. Emitting a single pulse of light can result in more than one reflection, providing an abundance of data that aids in accurate and precise analysis, especially in soil surface analysis in forested areas. In these cases, light can penetrate through the leaves, from the treetops to the middle trunks, and eventually hit opaque objects like the trunk or soil surface. These characteristics enable us to obtain data on the soil surface and tree trunk information, which makes the job much easier than it was in the past. The collection of these reflected light properties is referred to as "Multiple returns".
The concept of multiple returns is when a single wave emitted is reflected back in multiple values, due to the fact that the initial object does not absorb all the energy of the wave, allowing the wave to continue travelling in the same direction. It then hits a second, third, or even a fourth object until it reaches an opaque object that reflects it back. The wave penetrates until it encounters an opaque object which reflects back all the energy, and it cannot pass through any further. This type of reflection allows us to obtain a greater number of Point Clouds, which in turn makes the data gathered more precise in creating various models.
One of the latest advancements in LiDAR technology for drones is the DJI Zenmuse L2, which is designed to provide high-precision data collection capabilities. This cutting-edge sensor enables drone operators to capture accurate 3D representations of terrain and objects below, making it ideal for a wide range of industries such as construction, forestry, and infrastructure inspection. The DJI Zenmuse L2 offers obstacle penetration capabilities up until 5 returns, allowing it to gather data through vegetation and other obstacles with ease. With its ability to generate detailed Point Clouds, this sensor is revolutionizing the way data is collected and analyzed, making it an essential tool for professionals seeking precise and efficient mapping solutions.
In conclusion, LiDAR technology continues to revolutionize various industries by providing precise and detailed data collection capabilities. From creating digital terrain models unobstructed by vegetation to conducting flood modeling surveys and inspecting power lines, the applications of LiDAR are vast and ever-expanding. By utilizing Point Cloud technology, LiDAR enables accurate measurements, assessments, and planning in areas ranging from urban development to mining operations. The ability to penetrate obstacles and generate 3D representations of terrain opens up endless possibilities for innovation and problem-solving. As we look towards the future, the integration of LiDAR in metaverse tourism and virtual reality showcases the potential for even more exciting advancements. To explore further applications and stay updated on the latest developments in LiDAR technology, we encourage you to continue engaging with this fascinating field.