Underground lidar is a technology that allows for survey-grade mapping to generate high density point clouds in underground mines, stopes and civil tunnels. The data can be used by survey, mine planning, and geotechnical engineers. It uses lasers to measure the location and shape of all surfaces, measuring the distance by timing the return of the light. This allows the technique to be used as a remote sensing method. Lidar is used to create high-resolution data maps and 3D images of a surface.
Lidar sensing is used in surveys, geotechnical engineering, mapping, geology and other specialist applications. Increasingly, it is used to map underground environments, such as in the mining industry. This allows miners to measure their pit dimensions accurately, providing safety assurance.
What is lidar and how does it work?
Light imaging detection and ranging (lidar) is a sensing method to examine a ground surface, either on the earth, on built structures, or even underground. It is made up of a laser, a scanner, and photodetectors. Lidar can scan from a fixed location, like GeoLidar, or can be moved while scanning and the point clouds are combined through a processing algorithm called SLAM to reconstruct the scene, like AeroVoxel.
SLAM stands for Simultaneous Location and Mapping; a family of algorithms that use the lidar pointcloud data and inertial measurements from gyroscopes, accelerometers, magnetometers and temperature sensors to estimate the position and pose of the lidar scanner to reconstruct a point cloud of the scene. Naturally, these algorithms contain errors that are far greater than fixed lidar units where the scanner doesn’t move. Generally, SLAM systems provide 10 to 20mm of noise, whereas fixed lidars can achieve sub-mm accuracy. The tradeoff is fixed lidar units can have shadows or occlusions as their measurements are from a fixed position and line of sight, whereas SLAM units solve this by scanning from many positions.
Can lidar ‘see’ underground?
Lidar techniques can visualise spaces underground. It can determine the position or shape of objects to a high level of accuracy, and is also capable of sensing and mapping areas in low visibility conditions, such as underground or in low-light or constrained environments. Lidar cannot penetrate the ground or solid objects, but it can operate effectively throughout the day or night.
What is lidar technology used for?
Lidar underground mapping enables high-resolution surveying of mines. The technique can overcome the challenges inherent in an underground mine, such as being a GPS denied area, and having a constantly evolving shape and when placed on a drone, machine or robot, it can give detailed information about areas that are not accessible by humans – especially for open stopes. Lidar points clouds are used for mine planning, survey, mine reconciliation, drill and blast design, structural geology mapping, and geotechnical engineering uses such as convergence monitoring and change detection. SLAM mapping, such as AeroVoxel, can map large areas with little human intervention, as it can be mounted on a vehicle which drives through the mine. The maps and data sets can reveal the accurate, real-time changes in the mine. Repeated scanning can determine changes. This can inform decision making for surveyors, mine planners and geotechnical engineers.
Lidar use in mining
- The data capture and mapping features of lidar offers miners the ability to visualise their infrastructure. This provides better information to make decisions about safety, efficiency, and productivity.
- Lidar use in mining can collect data from challenged or GPS-constrained environments, such as underground or potentially unsafe sites.
- The maps provide remote inspection capabilities, allowing for structural analyses, convergence monitoring or the defect inspections.
Autonomous lidar solutions
To keep people away from mining sites until the stability has been determined, lidar solutions have developed to map areas without the need for humans to be near. For example, lidar solutions can be mounted on drones or vehicles to create autonomous mapping and navigation solutions. These are generally used to allow machines and robots to be guided or navigated to new locations and to discover new pieces of information in an underground mine.
Another solution is the merging of lidar with AI. Often times lidar will gain a full scan of an area, but the data it collects will be muddled with machinery, vehicles, or other non-geological phenomenons, requiring some human presence and observation to confirm if any significant ground movements have occurred.
Our solution, GeoLidar, uses AI to filter out the noisy data so human workers can be certain that their mining site is stable without the need to put anyone at risk. Not only does it increase safety, but productivity as well. The sooner you are certain that the site is safe, the sooner operations can commence.
Contact us for a free demo of GEOLIDAR or aerovoxel
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