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Methods to calibrate a three-sphere scale bar for laser scanner performance evaluation per the ASTM E3125-17
摘要： A scale bar with sphere targets is one way of realizing the symmetric and asymmetric length tests to evaluate Terrestrial Laser Scanner (TLS) performance per the ASTM E3125-17 standard. The length of the scale bar is required to be known with an expanded (k = 2) uncertainty that must be at least four times smaller than the manufacturer’s maximum permissible error (MPE) specification of the instrument being tested. In this paper, we propose two methods to calibrate the scale bar length using a laser tracker. The first method, which we refer to as the four-orientation and two-face (FOTF) method, is proposed for calibrating the scale bar when it is in a horizontal orientation. The other method, which we refer to as the comparison method, is proposed for calibrating the length of the scale bar in any orientation. We describe the methods, present underlying theories, discuss validation experiments, and summarize results. The two calibration methods are beneficial for the realization of the ASTM E3125-17 standard for TLS performance evaluation.
关键词： Three sphere scale bar,ASTM E3125-17,Terrestrial laser scanner,Laser tracker,Length calibration
更新于2025-09-16 10:30:52
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Leaf orientation measurement in a mixed hemiboreal broadleaf forest stand using terrestrial laser scanner
摘要： Orientation of leaves in a mature hemiboreal mixed broadleaf stand (the J?rvselja RAMI birch stand) was measured using the high-density point cloud of terrestrial laser scanner hits. Leaf normal distribution in the upper part of crowns of tall aspen and birch trees is almost spherical, and slightly planophile in the lower part of crowns. Leaves of alder trees are rather planophile in the upper part of crowns, and strongly planophile in the lower part of crowns. Lime and maple trees form the lower layer of trees in the stand. Their crowns are mainly in shade, and therefore, their leaf orientation is strongly planophile throughout the whole crown. Parameters of beta distribution and elliptical distribution are provided for the approximation of empirical distributions. The acquired information about leaf orientation can improve performance assessment of radiative transfer models.
关键词： Broadleaf forest,Foliage orientation,Terrestrial laser scanner
更新于2025-09-16 10:30:52
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Calibration and characteristics of an electrowetting laser scanner
摘要： We present a calibration method to correct for fabrication variations and optical misalignment in a two-dimensional electrowetting scanner. These scanners are an attractive option due to being transmissive, nonmechanical, having a large scan angle (±13.7?), and low power consumption (μW). Fabrication imperfections lead to non-uniform deposition of the dielectric or hydrophobic layer which results in actuation inconsistency of each electrode. To demonstrate our calibration method, we scan a 5 × 5 grid target using a four-electrode electrowetting prism and observe a pincushion type optical distortion in the imaging plane. Zemax optical simulations verify that the symmetric distortion is due to the projection of a radial scanning surface onto a flat imaging plane, while in experiment we observe asymmetrical distortion due to optical misalignment and fabrication imperfections. By adjusting the actuation voltages through an iterative Delaunay triangulation interpolation method, the distortion is corrected and saw an improvement in the mean error across 25 grid points from 43 μm (0.117?) to 10 μm (0.027?).
关键词： Laser scanner,Electrowetting,Scanning characteristic,Calibration
更新于2025-09-16 10:30:52
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Reliability of Terrestrial Laser Scanner Measurement in Slope Monitoring
摘要： Dense 3D point clouds provided by terrestrial laser scanner (TLS) has demonstrated significant reliability of TLS in landslide monitoring. However, existence of errors in measurement is inevitable which eventually has decreased the quality of TLS data. To concretely measure the capability of TLS in landslide monitoring, this study has performed two epoch measurements using tacheometry (for benchmarking) and TLS (Topcon GLS-2000) at Kulim Techno City, Kedah, Malaysia. Sixteen (16) artificial targets were well-distributed on the slope to determine the accuracy of the employed TLS. Results obtained revealed that Topcon GLS-2000 provides 0.006m of accuracy. However, the presence of high incidence angles in TLS measurement has limited the capability to identify the significant displacement of the targets.
关键词： Slope Monitoring,Incidence Angles,Terrestrial Laser Scanner,Landslide Monitoring,Accuracy
更新于2025-09-16 10:30:52
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Practical aspects of landslides surveys using terrestrial laser scanning in diverse geomorphological terrains: case studies from Polish Carpathians and Lower Vistula Valley
摘要： High-resolution digital elevation models from terrestrial laser scanning (TLS) in recent years have been more and more often used at various stages of landslide surveys. The article presents examples of TLS use in landslide research in areas that differ in morphogenesis: in mountains and in a lowland river valley. The examples concern the monitoring of mass movements from short and long distances (up to 3100 m), generation of differential models, and estimation of surface deformation. We also discussed the limitations of TLS measurements.
关键词： long-range terrestrial laser scanner,landslide monitoring,high-resolution digital elevation models,landslide surveys
更新于2025-09-16 10:30:52
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Multi-Temporal Cliff Erosion Analysis Using Airborne Laser Scanning Surveys
摘要： Rock cli?s are a signi?cant component of world coastal zones. However, rocky coasts and factors contributing to their erosion have not received as much attention as soft cli?s. In this study, two rocky-cli? systems in the southern Baltic Sea were analyzed with Airborne Laser Scanners (ALS) to track changes in cli? morphology. The present contribution aimed to study the volumetric changes in cli? pro?les, spatial distribution of erosion, and rate of cli? retreat corresponding to the cli? exposure and rock resistance of the Jasmund National Park chalk cli?s in Rugen, Germany. The study combined multi-temporal Light Detection and Ranging (LiDAR) data analyses, rock sampling, laboratory analyses of chemical and mechanical resistance, and along-shore wave power ?ux estimation. The spatial distribution of the active erosion areas appear to follow the cli? exposure variations; however, that trend is weaker for the sections of the coastline in which structural changes occurred. The rate of retreat for each cli?–beach pro?le, including the cli? crest, vertical cli? base, and cli? base with talus material, indicates that wave action is the dominant erosive force in areas in which the cli? was eroded quickly at equal rates along the cli? pro?le. However, the erosion proceeded with di?erent rates in favor of cli? toe erosion. The e?ects of chemical and mechanical rock resistance are shown to be less prominent than the wave action owing to very small di?erences in the measured values, which proves the homogeneous structure of the cli?. The rock resistance did not follow the trends of cli? erosion revealed by volume changes during the period of analysis.
关键词： cli? retreat,time-series analysis,cli? coastlines,airborne laser scanner
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Systems, Man and Cybernetics (SMC) - Bari, Italy (2019.10.6-2019.10.9)] 2019 IEEE International Conference on Systems, Man and Cybernetics (SMC) - Human Following of Mobile Robot With a Low-cost Laser Scanner
摘要： Human-following robots can bring a lot of convenience to our lives. The function of human-following can be decomposed into three processes: human detection, tracking and following. Considering cost and adaptability. In this paper, a low-cost laser scanner is used to achieve it. And an improved method of threshold-based clustering is proposed, which can effectively solve the problem of excessive clustering when it is far away from the laser scanner. Three types of features are extracted to recognize the legs from other objects by the random forest classifier. The position in the middle of the legs is used to indicate the position of the target person, which will be tracked by the robot using a Kalman filter algorithm and nearest neighbor algorithm. After inputting the coordinates of the followed target into the controller, the linear velocity and angular velocity of the following can be obtained. Experiments show that the robot can follow the target person stably.
关键词： Adaptive clustering,low-cost laser scanner,Human following
更新于2025-09-12 10:27:22
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Empirical stochastic model of detected target centroids: Influence on registration and calibration of terrestrial laser scanners
摘要： The target-based point cloud registration and calibration of terrestrial laser scanners (TLSs) are mathematically modeled and solved by the least-squares adjustment. However, usual stochastic models are simplified to a large amount: They generally employ a single point measurement uncertainty based on the manufacturers’ specifications. This definition does not hold true for the target-based calibration and registration due to the fact that the target centroid is derived from multiple measurements and its uncertainty depends on the detection procedure as well. In this study, we empirically investigate the precision of the target centroid detection and define an empirical stochastic model in the form of look-up tables. Furthermore, we compare the usual stochastic model with the empirical stochastic model on several point cloud registration and TLS calibration experiments. There, we prove that the values of usual stochastic models are underestimated and incorrect, which can lead to multiple adverse effects such as biased results of the estimation procedures, a false a posteriori variance component analysis, false statistical testing, and false network design conclusions. In the end, we prove that some of the adverse effects can be mitigated by employing the a priori knowledge about the target centroid uncertainty behavior.
关键词： stochastic model,target centroid detection,calibration,registration,terrestrial laser scanner
更新于2025-09-12 10:27:22
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Laser-based imaging applications in turbid waters
摘要： Underwater laser-based imaging systems and data-processing techniques matured during the past decade. Active imaging systems can, nowadays, be integrated into platforms like remote-operated vehicles (ROV) or autonomous underwater vehicles (AUV). This article gives an overview of different civil and naval applications in underwater imaging with respect to underwater laser scanning (ULS) and laser gated viewing (LGV). Special emphasis has to be given to the environmental conditions, for example, the influence of the local and seasonal dependence of the turbidity with regard to the optical underwater channel. On the basis of tank and sea experiments, advanced techniques for 3D laser oblique scanning (LOS) and possibilities of contrast enhancements for gated viewing are presented.
关键词： laser scanner,laser gated viewing,underwater laser imaging,post-processing
更新于2025-09-11 14:15:04
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - A Compact Omnidirectional Laser Scanner Based on an Electrothermal Tripod Mems Mirror for Lidar Please Leave
摘要： Low-cost LiDAR with compact omnidirectional 360° scanners are needed for automobiles and robotics. This paper reports a compact omnidirectional scanner based on an electrothermal MEMS mirror, in which a circular pattern is generated by a two-axis tripod electrothermal MEMS mirror at non-resonant mode combined with a cone mirror. Meanwhile the vertical scanning field of view (FoV) up to 8° is also achieved. Compared to other omnidirectional scanners based on motorized optomechanics, this MEMS-based omnidirectional scanner has the potential to greatly decrease the size, cost and power consumption for LiDAR.
关键词： LiDAR,Omnidirectional,Non-resonant scanning,Micromirror,Laser Scanner,Electrothermal acutator
更新于2025-09-11 14:15:04