Eyes in Flight - Airborne Lidar
Airborne lidar
Since the development of Lidar technology in the 1960s, airborne Lidar technology has gradually developed as an important aerial remote sensing technology, and has attracted the attention of scholars, researchers, lidar suppliers and so on. Although airborne Lidar can not completely replace the traditional measurement operation mode, it can be predicted that in the future aviation remote sensing field, airborne Lidar will become one of the mainstream. In the 1990s, airborne LiDAR system began to gradually enter the practical stage, and became one of the important directions of the development of LiDAR as remote sensing equipment. After entering the 21st century, people's demand for high-end technology is getting higher and higher, and the degree of attention to emerging technologies is also getting higher and higher. Airborne Lidar has gradually been applied to all walks of life, while many manufacturers have gradually smelled the business opportunities, began to increase investment in airborne Lidar. At present, airborne Lidar in urban and rural planning, architectural mapping, terrain mapping, security monitoring and inspection, environmental protection testing, agriculture and forestry testing, disaster prevention and reduction and other fields have its figure.
Application status of airborne radar
Airborne radar, with its advantages of high precision, high resolution, high automation and high efficiency, has become an important mainstream and trend of large-scale numerical surface data measurement in countries around the world. Its multiple reflection characteristics can simultaneously obtain the accurate three-dimensional coordinates of the ground and its cover (vegetation, power lines, etc.), while the permeable lidar system can penetrate the water and measure the relief of the bottom of the terrain. The high-precision and high-resolution DEM obtained can be used as the application basis for land use, engineering construction planning, urban planning management, river and sea topography, intertidal zone, catchment area, hillside detection, geographic information system, disaster prevention, mining, agriculture, forestry, public management line and other aspects of numeralization and automation.
1. Smart city
In today's increasingly high degree of digitization, the two-dimensional urban system can no longer meet the needs of the new era, and the complete presentation of the three-dimensional space image has become an inevitable development, and is also the requirement of "digital Earth". Therefore, the rapid acquisition of three-dimensional spatial data, simulation and reproduction of real life put forward higher requirements. Radar system in the city can better reflect its advantages of not being restricted by flight height, shadow occlusion, etc., can quickly collect three-dimensional spatial data and images, fast building modeling speed, high elevation accuracy, high degree of texture mapping automation, can meet the needs of analysis and measurement, and is widely used in large-scale topographic map acquisition of urban planning. Airborne Lidar plays an important role in smart cities, and it plays an unusual role in many aspects such as intelligent transportation, terrain mapping, and smart city planning. Nowadays, major cities in China are gradually laying out smart cities and digital cities, in which airborne Lidar plays a great role in obtaining data and scanning the status quo of the city.
2. Engineering construction survey
Airborne LiDAR measurements can provide accurate elevation data for road engineering and other construction projects. The DEM generated by airborne LiDAR combined with GIS and CAD software enables designers to simulate various schemes to select the best route or the best location. For the original prediction of construction money, DEM combined with orthophoto can provide engineers with the vast amount of topographic and survey information they need.
Figure 2: DEM from LiDAR terrain mapping
3. Electric power design survey line selection and line monitoring applications.
With the continuous improvement of transmission line voltage level, the safe, stable and efficient operation of transmission line patrol is becoming more and more important. The transmission lines are distributed across regions, the points are wide, and the terrain is complex. The transmission line equipment is exposed to the field for a long time, and is affected by continuous mechanical tension, lightning flashover, material aging, icing and human factors, which will cause broken strands, wear, corrosion and other phenomena, and must be repaired or replaced in time.
The traditional manual line inspection method is not only heavy workload and difficult conditions, especially the inspection of transmission lines in mountainous areas and across large rivers, which takes a long time, high labor cost and great difficulty, and some line areas and some inspection items are still difficult to complete.
Based on airborne LiDAR technology, the full range of 3D visual geographic information data of the power line corridor environment can be quickly extracted from the distance between the power line and the vegetation along the vertical and horizontal direction, and the security risks can be quickly identified. When designing power lines at the same time, the terrain and feature elements in the whole line design area can be known through radar data.
Figure 3: LiDAR applications in power line corridors
4. Disaster monitoring and environmental monitoring
Using the DEM generated by airborne liDAR, hydrologists can predict the extent of flooding, develop disaster mitigation plans, and remedy measures. A typical airborne LiDAR system can survey a 30km area in four hours using a fixed-wing aircraft. With a vertical accuracy of 15cm and an average point distance of 1.5m, it recorded a total of 153m data points reflecting detailed terrain and features. It is also widely used in post-disaster assessment and response to natural disasters (such as hurricanes, earthquakes, floods and landslides, etc.).
In May 2017, the Japanese government deployed a liDAR mapping system to assess the damage caused by the 2016 Kumamoto earthquake. The data obtained are used to develop strategies for the effective provision and allocation of relief resources in the event of such emergencies. Lidar in mapping systems has been widely used to geo-mark earthquake-prone areas and to assess the impact of landslides caused by earthquakes.
Figure 4: LiDAR monitoring in natural disasters
5. Coastal engineering
Traditional photogrammetry techniques sometimes cannot be used in areas with low contrast or no distinct features, such as coasts and coastal areas. In addition, the dynamic environment of coastal areas also requires frequent updating of baseline data. Airborne Lidar is an active sensing technology, which can do conventional basic coastline measurement under high dynamic environment at low cost, and has a certain underwater detection capability, which can measure underwater terrain within 70m offshore water depth, and can be used for three-dimensional measurement and dynamic monitoring of coastal zones, seaside dunes, seaside guard and coastal forests.
6. Forestry applications
One of the first commercial applications of airborne Lidar systems is in the forest industry, where foresters and land managers need accurate data on the forest and beneath the canopy. Under traditional techniques, tree height and tree density are difficult to obtain information. In the post-processing of the data, the independent laser return value can be divided into vegetation return value and ground return value, and according to the radar data, the coverage rate and cover area of the forest trees are analyzed to understand the density of the trees, the cover area of the older trees and the cover area of the younger trees. Through the radar data, the forest area and the average height of the trees can be estimated, and the amount of wood is much easier for the relevant departments to carry out macro-control.
East China Survey, Planning and Design Institute of the National Forestry and Grassland Administration successfully applied airborne Lidar to the annual dynamic monitoring of forest resources in Anhui Province, obtained the forest stock by using the accurate ranging ability of Lidar, and applied it to the Yunzhen Forest Platform of the self-developed Anhui forest resources "One Map" application system. It can quickly and accurately obtain the forest coverage rate and forest stock, and achieve the annual number of forest resources.
In the past two years, the Forestry Bureau of Guangxi Zhuang Autonomous Region has conducted a pilot survey of forest resource planning and design by applying new technologies such as Lidar, and the field manpower and time investment have been reduced by 80%-90% compared with traditional methods. The two practices of the East China Institute and Guangxi mean that the use of LiDAR technology combined with multi-source data for forest resource monitoring can not only reduce the difficult forest resource field investigation work, but also obtain the forest area and forest stock efficiently, quickly and objectively.
Figure 5: Application of LiDAR in forestry monitoring
7. Protection of cultural heritage
Large cultural relics and outdoor immovable cultural relics need to measure their three-dimensional data for restoration and protection. For artifacts in harsh measurement environments or that cannot be directly touched, radar technology becomes a good solution to directly acquire three-dimensional data.
Figure 6: Application of Lidar in the protection of cultural sites
8. Oil and gas exploration
Survey procedures in the oil and gas industry often require the rapid transmission of data related to topographic data XYZ in a short period of time. While there are a variety of ways to handle collecting location data, airborne Lidar measurements are a high-speed and non-contact method of data acquisition, and in most cases, it takes only a few weeks from the start of exploration to the final data transmission. In some complex environmental areas, the cost of cutting down trees can be thousands of dollars per hectare. Such as airborne lidar survey, only a few lines of trees need to be cut down, which can save a lot of money and reduce the impact on the environment.
In July 2019, Terra Drone Brazil, a Brazilian oil and gas detection service provider, conducted extensive aerial lidar mapping for Petrobas, a Brazilian state-owned energy company. The liDAR mapping identified corrosion, cracks and surface weld defects in the fuel storage facility's cargo and ballast tanks. This contributes to Petrobas' timely maintenance and business continuity.
Three-dimensional Lidar technology is the world's leading space technology to achieve synchronous, rapid and high-precision acquisition of three-dimensional spatial coordinates and image data, and has a huge advantage in the acquisition of surface data that traditional aerial photogrammetry cannot match. Airborne Lidar is the "eye" in flight, it is another technological innovation in the field of surveying and mapping since GPS, is a revolution in high-precision reverse three-dimensional modeling and reconstruction technology, is a weapon for large-area space exploration, and is the only way for digital China and various industries to digitize. It will have a profound impact on power grid, water conservancy, transportation, planning, land, mining, Marine, meteorology, agriculture, forestry, historic site protection and other fields.
Airborne Lidar market
In 2018, ASDReports released the "Global Airborne Lidar Systems Market, Analysis and Forecast 2017-2021" market intelligence research report, the global airborne Lidar systems market is expected to reach $1.55 billion by the end of 2021, with an average compound growth rate of 16.1% during the 2016-2021 period. In the last decade, there has been a revolution in remote sensing technology, resulting in the addition of new airborne mapping/mapping technologies such as light detection and ranging (LiDAR). In recent years, airborne radar has gained traction because of the high efficiency and high cost ratio remote sensing data.
In 2020, according to research by global market Insights, the global Lidar market in the field of mapping is expected to exceed $4 billion by 2026.
Figure 7: Airborne LiDAR market forecast
According to another forecast report mentioned on Yahoo Finance, the key factors driving the growth of the drone Lidar market include the relaxation of regulations related to the use of commercial drones in different applications, and the growing demand for LiDAR drones for corridor mapping and precision agriculture applications. However, regulations related to the use of drones in different countries are also expected to slow the growth of this market to a certain extent during the forecast period. From 2020 to 2025, the drone market in Asia Pacific (LiPAC) is expected to grow at the highest CAGR. The airborne Lidar market in Asia Pacific is expected to grow at the highest CAGR during the forecast period. The growth of the market in this region can be attributed to the increase in the amount of infrastructure, increased use of airborne Lidar in mapping applications development projects, government emphasis on forest management, and increased mining activities in this region. In addition, moderate government policies related to the use of UAV radars in the region and the easy availability of low-cost UAV lidar in the region are expected to drive the growth of the airborne lidar market in the Asia-Pacific region during the period.
Ouster Lidar
Ouster is an American liDAR manufacturer that has emerged in recent years, with nine products in three series, namely OS0-32, OS0-64, OS0-128, OS1-32, OS1-64, OS2-128, OS2-32, OS2-64, OS2-128. Its lidar has a light weight, the smallest 445g, the heaviest but 930g; The detection distance is long, up to 200-300 meters; High precision, its laser radar resolution can reach ±5-10cm. Ouster Lidar is very suitable for use in drones. Today, ouster LiDAR has been used in UAV mapping, agriculture and forestry monitoring, field animal monitoring and many other fields.
Figure 8: ouster LiDAR UAV application
