Nowadays, lidar technology has been operationally used in different applications by many firms and organizations. In some specific instances, using traditional techniques will take a lot of time and cost from the customers to meet their needs. For example, many hydrography and oceanography require bathymetric maps for close coastline areas.
Besides, using echo-sounders would be vicious, inaccurate enough when used in shallow waters, time-consuming, and can’t give a continuous water bottom. Otherwise, the use of lidar systems provides fast depth data from a large region. Therefore, there’s no need to contact the water body directly.
This ability solves most industrial and military requirements for perfect and exact geospatial information from the water superficial area rapidly. In this article, a comprehensive overview of lidar, airborne lidar uses, and its application is tackled.
By definition
Airborne lidar
This is a changing, polar, and active multi-detector system comprising a map-reading unit for continuous determination of the sensor platform’s position and attitude and the laser the scanner itself. This gives the direction of the laser beams and the distance between the detector and the bouncing targets.
About airborne imaging’s lidar technology
Airborne imaging has been a leading provider of airborne lidar since its launch in 2004. The company prioritized from the outset to use the only commercial, off the shelf lidar systems from world-renowned producers. It has currently acquired hundreds of thousands of square miles of airborne lidar data in most North American parts. Nevertheless, regardless of point density or accuracy, it has a versed knowledge of the flight plan, field executes, post-processing, and a refined map standard lidar topography to its clients.
Examples of airborne lidar systems
- A dynamic differential GPS receiver
- Laser scanners
- Lidar rangefinders
- Inertial measurement unit (IMU)
- Central control unit management
- Imaging devices (usually digital aerial instrument)
What is lidar
Lidar, which is also an acronym of light-detecting ranging, gathers laser, measure distances, and computer IMU( Inertial measurement unit) in the integral whole. The technology has resulted in a tremendous breakthrough of real-time data acquisition of 3D space information and its new means of acquiring high-space resolution geospace information.
Lidar quickly gets the elevation data and brings about several techno-breakthrough in remote sensing mapping and other fields. It holds extensive development foreground in topography surveying and mapping environmental supervising 3D urban modelling, ocean science, and planetary science. Additionally, lidar technology possesses higher automatization features, low weather influences, shorter data production period, and high precision than any other remote sensing systems.
Lidar positioning principle
A lidar study’s procedure is to fly an aircraft over a particular area and operate laser scanning from side to side. Usually, the receiver picks up laser surges bouncing vale of the target and records the time taken from emission until it is received back to the receiver. In case this time is divided by two and multiplied by the speed of light, then that is the distance of the helicopter o the ground.
The inertial system monitors the aircraft’s rotations in three axes, and the GPS trails the aeroplane’s real location in space. Lidar is a piece of equipment through location, angle, and other data observation to access the 3D surface target coordinates directly, its technological advancement after global positioning in mapping and surveying fields.
Processing of lidar data
The initial data acquired by airborne lidar can be melt with all types of digital images just after processing by the software, capable of outputting all kinds of survey and remote sensing products. The entire flow of preparing information from data assembling to production output can be divided into five sections. This includes;
- Data pretreatment
- Collection of data
- Filter and classification of point cloud
- Fusion
- Application of lidar and another remote sensing
Lidar for drones
Drones for mapping and 3D have improved rapidly over recent years. Mapping drones have larger payloads and long flight times and can be equipped with navigation technology and detectors. Some drones can now be fitted with laser sensors to collect data for three-dimension point cloud terrain models. This is a cheap method for performing surveys of small areas as compared to surveys with helicopters. Additionally, drones equipped with laser scanners are used mostly to study rough terrain or remote areas.
Advantages of lidar technology
- Lidar systems have numerous apparent advantages. It has an active laser surge detector, and it’s not regulated by the sun’s shadow angle, minimizing its influence on data acquisition.
- Compared with photogrammetry systems, it prevents information loss and has higher elevation accuracy.
- It uses a multi-beam echo to acquire a precise data density.
- A significant reduction in ground monitoring surveys and air flight routes can automatically increase automation levels and generate digital elevation models.
Application of airborne lidar
Since the advancement of laser survey technology, getting 3D information has been easy and cost-effective. Sectors like civil engineering highly depend on three-dimension information to assess and operate most of its applications and projects, making lidar study an essential thing. Aerial laser scrutiny has been a game-changer in most civil engineering and other sectors.
Besides, lidar study is a surveying technique that determines the distance to a target by elucidating earmark with laser light. It has been confirmed to be of help in the construction and maintenance of dams, pipelines, and highways. Drone technology is advancing rapidly and provides prudent alternatives for traditional airborne lidar surveying using aeroplanes or helicopters. Nevertheless, these surveys are often cheaper, faster, safer, and more effective.
- Flood mapping and catchment survey
Aerial lidar survey and modern imagining are essential in managing water catchment areas and practical study of such places. Nevertheless, it has proved to be important in the handling of infrastructure and land use mapping. It has also confirmed significant flood mapping, generating information on emergency response designing, evacuation planning, and the drainage of surface water.
Besides, it offers spatial info about the vegetation cover in urban centres. For instance, laser surveying in Panama has helped in protecting watersheds and cadastral studies. The same has also worked in Florida, where the lidar survey has played a significant role in catchment surveys, terrain analysis, and forest management.
- Urban planning
Through three dimensions, laser techniques have provided engineers with vital information for urban centres drafting. By providing views of suggested works in existing landscapes, laser surveying offers scanning and preparation of vegetation cover in recreational centres and residential areas. For example, aerial photogrammetry and lidar survey is what the state of Florida uses for urban organization purposes.
Besides urban planning, laser services have helped in transportation, management, design, and telecommunication systems optimization. These go together with city planning making lidar a perfect choice for the urban organization.
- Dam surveying
This can be approached in two ways, either airborne laser hydrography or topography lidar. The former utilizes two surging laser beams, while the latter uses one of the laser beams. Besides, both of them are necessary for dam surveying. It maximizes topological accuracy and minimizes the time used for the study and the cost. Its role in visibility study has helped in discerning if a project is viable or not. Despite airborne laser being a technology to venture into, few are interested in it.
- Power line inspection
Detailed information on power lines and the distance between poles can be extracted from the point of cloud. This enhances surveyors to scrutinize the power line corridors’ structure, including vegetation, roads, and houses, to identify potential risks.
- Forestry and precision agriculture
Laser and aerial photos can be used to identify farm areas that need expensive fertilizers to raise productivity. It is also essential in precision forestry to identify specific forest areas to increase production, minimize cost, and protect the environment.
- Mining
Lidar systems are necessary for mining to measure ore extraction space. This is arrived at by comparing the surface data to the previous scanning. Besides, drones are often used to scrutinize mines because of a faster and more economical option than surveying using airplanes. Terrestrial laser scanners and mobile mappers are usually equipped with detectors that are also used to survey mines.
- Land surveying
Airborne laser scanners can be used to generate a digital terrain model or a digital elevation structure. Information can be collected using a drone, airplane, or helicopter based on the surveyed area’s size. Usually, drones are much cheaper, safer, and faster for small area surveys.
My final thoughts
Aerial laser systems are rapidly advancing and expanding in new applications. In this article, we have focused on hydrology and oceanography, among others. A fair comparison has been outlined among all the available detectors, and lidar sensors seem to be a useful sensor for this role.
This reveals that laser sensors provide a rapid and cheap hydrological tool, mostly for coastal and river water management. However, there’re some weaknesses in the lidar data segmentation, visualization, water wave estimation, and low depth measurement. The integration of lidar with imaging detectors and useful processing algorithms would help obtain more real and precise three-dimensional models of geospatial objects.
