Continuous-Time Three-Dimensional Mapping for Micro Aerial Vehicles with a Passively Actuated Rotating Laser Scanner

Abstract

The ability to generate accurate and detailed three‐dimensional (3D) maps of a scene from a mobile platform is an essential technology for a wide variety of applications from robotic navigation to geological surveying. In many instances, the best vantage point is from above, and as a result, there is a growing demand for low‐altitude mapping solutions from micro aerial vehicles such as small quadcopters. Existing lidar‐based 3D airborne mapping solutions rely on GPS/INS solutions for positioning, or focus on producing relatively low‐fidelity or locally focused maps for the purposes of autonomous navigation. We have developed a general‐purpose airborne 3D mapping system capable of continuously scanning the environment during flight to produce accurate and dense point clouds without the need for a separate positioning system. A key feature of the system is a novel passively driven mechanism to rotate a lightweight 2D laser scanner using the rotor downdraft from a quadcopter. The data generated from the spinning laser is input into a continuous‐time simultaneous localization and mapping (SLAM) solution to produce an accurate 6 degree‐of‐freedom trajectory estimate and a 3D point cloud map. Extensive results are presented illustrating the versatility of the platform in a variety of environments including forests, caves, mines, heritage sites, and industrial facilities. Comparison with conventional surveying methods and equipment demonstrates the high accuracy and precision of the proposed solution.

Possibilities for Using Lidar and Photogrammetric Data Obtained With an Unmanned Aerial Vehicle for Levee Monitoring

“…Low-altitude UAV data may be quickly organized, which is a less expensive solution than the use of an aeroplane with the ALS system. Although the workflow presented in this paper is relatively wide, it is worth noticing that it requires less time than methods based on dense image matching and accessible technological solutions using the RTK method allow online access to acquired data (Kaul et al, 2015).…”

Estimation of deep infiltration in unsaturated limestone environments using cave lidar and drip count data

“…However, karstic model development using T-LiDAR is a novel application. There are few studies that discuss the benefits and the use of this tool, as well as the methods needed to work with this kind of technology (exceptions are Bosse, 2014b, a, andKaul et al, 2016). We have used a FARO Focus3D Terrestrial LiDAR to acquire threedimensional geological images of the cave ceiling, which is capable of capturing millions of three-dimensional points coordinates within a few minutes.…”

“…However, LiDAR just provides a onceoff snapshot and does not capture the temporal variability of actively dripping stalactites. Therefore, repeat surveys based on LiDAR are feasible (Zlot and Bosse, 2014b, a;Kaul et al, 2016) and would be a rapid and easy way of looking at changes over time. …”

Evaluating Continuous-Time Slam Using a Predefined Trajectory Provided by a Robotic Arm

“…Lehtola et al (2016) built an experimental mobile mapping system based on a FARO scanner and a rolling wheel. Similarly, constantly rotating scanners were used in the setups of (Zhang and Singh, 2014;Kaul et al, 2016;Nüchter et al, 2015). The task of continuous Time SLAM is to deform or transform the trajectory, such that the quality of the point cloud is improved.…”

“…In contrast to this, offline SLAM provides a post-processing step for separate 3D point clouds. Recently, continuous-time SLAM approaches are used to optimize the trajectories acquired during mobile mapping (Barfoot et al, 2014;Anderson et al, 2015;Bosse et al, 2012;Lehtola et al, 2016;Zhang and Singh, 2014;Kaul et al, 2016). This is for example achieved by globally consistent scan matching to find an optimal alignment of 2D profiles to increase the inner accuracy of the point cloud.…”