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Reconstructing Aircraft Trajectories from Multi-Return Airborne Laser-Scanning Data
摘要： Data describing aircraft position and attitude are essential to computing return positions from ranging data collected during airborne laser scanning (ALS) campaigns. However, these data are often excluded from the products delivered to the client and their recovery after the contract is complete can require negotiations with the data provider, may involve additional costs, or even be infeasible. This paper presents a rigorous, fully automated, novel method for recovering aircraft positions using only the point cloud. The study used ALS data from five acquisitions in the US Pacific Northwest region states of Oregon and Washington and validated derived aircraft positions using the smoothed best estimate of trajectory (SBET) provided for the acquisitions. The computational requirements of the method are reduced and precision is improved by relying on subsets of multiple-return pulses, common in forested areas, with widely separated first and last returns positioned at opposite sides of the aircraft to calculate their intersection, or closest point of approach. To provide a continuous trajectory, a cubic spline is fit to the intersection points. While it varies by acquisition and parameter settings, the error in the computed aircraft position seldom exceeded a few meters. This level of error is acceptable for most applications. To facilitate use and encourage modifications to the algorithm, the authors provide a code that can be applied to data from most ALS acquisitions.
关键词： simulation,aircraft position,pulse angle,trajectory,automation,airborne laser scanning
更新于2025-09-16 10:30:52
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Scanning a Silicon Photomultiplier with a Laser Beam
摘要： The Silicon Photomultiplier (SiPM) is a novel semiconducting photodetector which can detect single photons. It consists of many microcells (pixels) operating in the so-called Geiger mode. At present, there are two principal designs among such devices: surface pixel and deeply buried pixel (microwell) structures. The cellular structure decreases the device’s effective photosensitive area, expressed in terms of the geometrical fill factor. It is very important to take it into account when developing new constructions with high pixel densities that are necessary for increasing the dynamic range. It is believed that the fill factor of deep microwell SiPMs is close to unity. In this work, the technique and results of studying the zonal response of different SiPMs by scanning (moving) with micron laser spot are presented. It is shown that the geometrical fill factor of the deep microwell SiPM is less than 100% when detecting the red light (λ = 632 nm).
关键词： Silicon Photomultiplier,Geiger mode,geometrical fill factor,laser scanning,deep microwell SiPM,SiPM
更新于2025-09-16 10:30:52
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Thermal Infrared Imagery Integrated with Terrestrial Laser Scanning and Particle Tracking Velocimetry for Characterization of Landslide Model Failure
摘要： A laboratory model test is an effective method for studying landslide risk mitigation. In this study, thermal infrared (TIR) imagery, a modern no-contact technique, was introduced and integrated with terrestrial laser scanning (TLS) and particle tracking velocimetry (PTV) to characterize the failure of a landslide model. The characteristics of the failure initiation, motion, and region of interest, including landslide volume, deformation, velocity, surface temperature changes, and anomalies, were detected using the integrated monitoring system. The laboratory test results indicate that the integrated monitoring system is expected to be useful for characterizing the failure of landslide models. The preliminary results of this study suggest that a change in the relative TIR signal (?TIR) can be a useful index for landslide detection, and a decrease in the average value of the temperature change (?TIR) can be selected as a precursor to landslide failure.
关键词： landslide failure,thermal infrared imagery,terrestrial laser scanning,particle tracking velocimetry
更新于2025-09-16 10:30:52
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Examination of the Potential of Terrestrial Laser Scanning and Structure-from-Motion Photogrammetry for Rapid Nondestructive Field Measurement of Grass Biomass
摘要： Above ground biomass (AGB) is a parameter commonly used for assessment of grassland systems. Destructive AGB measurements, although accurate, are time consuming and are not easily undertaken on a repeat basis or over large areas. Structure-from-Motion (SfM) photogrammetry and Terrestrial Laser Scanning (TLS) are two technologies that have the potential to yield precise 3D structural measurements of vegetation quite rapidly. Recent advances have led to the successful application of TLS and SfM in woody biomass estimation, but application in natural grassland systems remains largely untested. The potential of these techniques for AGB estimation is examined considering 11 grass plots with a range of biomass in South Dakota, USA. Volume metrics extracted from the TLS and SfM 3D point clouds, and also conventional disc pasture meter settling heights, were compared to destructively harvested AGB total (grass and litter) and AGB grass plot measurements. Although the disc pasture meter was the most rapid method, it was less effective in AGB estimation (AGBgrass r2 = 0.42, AGBtotal r2 = 0.32) than the TLS (AGBgrass r2 = 0.46, AGBtotal r2 = 0.57) or SfM (AGBgrass r2 = 0.54, AGBtotal r2 = 0.72) which both demonstrated their utility for rapid AGB estimation of grass systems.
关键词： Structure-from-Motion (SfM) photogrammetry,disc pasture meter,grass,aboveground biomass (AGB),compact biomass LiDAR (CBL),terrestrial laser scanning (TLS),volume
更新于2025-09-16 10:30:52
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Evaluation of Factors, Influencing the Accuracy of the Digital Model, Obtained by Laser Scanning
摘要： Measurements in terrestrial laser scanning (TLS) are not perfect and are subject to errors caused by various factors affecting the quality of the capture process and the resulting final product. Careful consideration of all these factors and errors provides a good basis for assessing the quality of the data and the information received. The accuracy of the 3D model obtained from laser scanning is influenced by the density of the measurements and the modelling methods. 3D modelling algorithms allow accuracy to be improved, but modelling software cannot solve all the problems, and it is impossible to achieve high quality 3D modelling without taking into account the factors that affect the accuracy of the measurements. The investigation of error sources in TLS measurements is rather complicated due to the large number of influencing factors that are interconnected. In addition to angular and longitudinal measurements, most scanning systems also offer a measure of the intensity of the reflected signal. Because the TLS is a non-reflective geodetic technology, it means that the measurement results are highly dependent on the reflectivity of the materials. The energy of the reflected signal depends on the following physical factors: object material properties, surface colour of the object, surface temperature, surface humidity, illumination. From the experimental studies it has been confirmed that the illumination and humidity of the scanned surfaces have a significant impact on their reflecting ability and the density of the received point cloud. Evaluation of digital model accuracy is made with а plane approximation and comparison with control points. Areas with different point densities were created in order to analyse the accuracy of 3D model and to determine the optimum scanning density.
关键词： accuracy,illumination,humidity,terrestrial laser scanning,TLS,point cloud,3D model,reflectivity
更新于2025-09-16 10:30:52
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3D laser scanning for monitoring the quality of surface in agricultural sector
摘要： The paper considers three technologies for obtaining data on the road surface - through video recording, thermal imaging and laser scanning for the purpose of monitoring, diagnostics and control of the road quality. An analysis of the first two methods showed their significant drawbacks, such as the inability to measure the geometric parameters of deformations (video recording) and the significant dependence of the measurement results on external conditions (thermal imaging). Laser scanning, on the contrary, has a number of advantages, including coordinate referencing, obtaining a three-dimensional model, its transformation and measurement of parameters. Laser scanning is widely used, but mainly for measuring the quantitative characteristics of objects. The paper discusses the application of the laser scanning method to determine the qualitative characteristics of the road surface - the presence or absence of defects, which include hollow spots, waves, cavities, chipping, bleeding, humps, cracks, vertical displacement of road plates, rutting, unevenness of patching, damage to the road surface, track, breach, destruction of the pavement edge, subsidence followed by a complex of repair work. For this, a ground-based laser scanning was performed, the results of which were processed using the Leica Cyclone 9.4 software. According to the scanning data, defects were detected in the form of soil subsidence, hollow spots and humps. The performed work revealed a drawback of the laser scanning method, which consists in the absence of automated detection and recognition of deformations. A number of measures have been proposed to improve this drawback, which slows down the randomness and quality of work in monitoring and diagnosing the road. Further prospects for research on this topic, in particular the multi-purpose use of scanning data, by creating a distributed ledger are also indicated.
关键词： agricultural sector,3D laser scanning,road surface quality,monitoring,defects detection
更新于2025-09-16 10:30:52
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Damage Diagnosis of Reactive Powder Concrete under Fatigue Loading Using 3D Laser Scanning Technology
摘要： Damage mechanisms of Reactive Powder Concrete (RPC) under fatigue loading are investigated using the 3D laser scanning technology. An independently configured 3D laser scanning system is used to monitor the damaging procedure. Texture analysis technique is also applied to enhance the understanding of the damage mechanisms of RPC under fatigue loading. In order to obtain the characteristic parameters of point cloud data, a point clouds projection algorithm is proposed. Damage evolution is described by the change of point cloud data of the damage in the 2D plane and 3D space during fatigue loading. The Gray Level Co-occurrence Matrix (GLCM) method is used to extract the characteristic parameters to evaluate the statue of the structural. Angular Second Moment and Cluster Shadow of typical sensitive characteristic indexes is screened by using the Digital Feature Screening. The reliability of the damage index was verified by image texture analysis and data expansion. Indexes extracted in this paper can be used as a new structural health monitoring indicator to assess health condition.
关键词： damage monitoring,texture analysis,feature extraction,gray level co-occurrence matrix,image processing,3D laser scanning
更新于2025-09-16 10:30:52
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Observation of the process of snow accumulation on the Antarctic Plateau by time lapse laser scanning
摘要： Snow accumulation is the main positive component of the mass balance in Antarctica. In contrast to the major efforts deployed to estimate its overall value on a continental scale – to assess the contribution of the ice sheet to sea level rise – knowledge about the accumulation process itself is relatively poor, although many complex phenomena occur between snowfall and the definitive settling of the snow particles on the snowpack. Here we exploit a dataset of near-daily surface elevation maps recorded over 3 years at Dome C using an automatic laser scanner sampling 40–100 m2 in area. We find that the averaged accumulation is relatively regular over the 3 years at a rate of +8.7 cm yr?1. Despite this overall regularity, the surface changes very frequently (every 3 d on average) due to snow erosion and heterogeneous snow deposition that we call accumulation by “patches”. Most of these patches (60 %–85 %) are ephemeral but can survive a few weeks before being eroded. As a result, the surface is continuously rough (6–8 cm root-mean-square height) featuring meter-scale dunes aligned along the wind and larger, decameter-scale undulations. Additionally, we deduce the age of the snow present at a given time on the surface from elevation time series and find that snow age spans over more than a year. Some of the patches ultimately settle, leading to a heterogeneous internal structure which reflects the surface heterogeneity, with many snowfall events missing at a given point, whilst many others are overrepresented. These findings have important consequences for several research topics including surface mass balance, surface energy budget, photochemistry, snowpack evolution, and the interpretation of the signals archived in ice cores.
关键词： snow deposition,surface elevation,Antarctic Plateau,laser scanning,snow accumulation,snow erosion
更新于2025-09-16 10:30:52
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Using Weighted Total Least Squares and 3-D Conformal Coordinate Transformation to Improve the Accuracy of Mobile Laser Scanning
摘要： With the aid of global position system (GPS), mobile laser scanning (MLS) is able to provide 3-D geo-referenced point cloud that has centimeter-level accuracy. The MLS accuracy, however, degrades signi?cantly due to the trajectory errors of the laser scanner and the residual systematic errors from the geo-referencing transformation process in the GPS-free environments. To solve this problem, this article presents a novel integration algorithm based on the weighted total least squares (WTLS) and the 3-D conformal coordinate transformation (3DCCT). In this new method, the 3-D point measurement model and the error propagation parameter vector in the MLS can be updated in real-time, and they can also adjust the geo-referenced coordinate transformation parameters and eliminate the in?uences of the residual systematic errors during MLS. In this article, the MLS mathematical model is ?rst established, followed up by a detailed analysis for MLS error budget interpreting the effects of the individual error sources. Second, WTLS is used to correct the 3-D point measurement model of MLS and the error of propagation parameter vector; 3DCCT, WTLS, and ground control target feature constraints are applied to eliminate the residual systematic errors in the geo-referencing transformation process. Finally, several data sets from outdoor scenarios are used to evaluate and validate the proposed method. The experimental results demonstrate that the proposed method can signi?cantly improve the overall accuracy of the MLS system.
关键词： mobile laser scanning (MLS),weighted total least squares (WTLS),3-D conformal coordinate transformation (3DCCT)
更新于2025-09-16 10:30:52
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Tunnel Monitoring and Measuring System Using Mobile Laser Scanning: Design and Deployment
摘要： The common statistical methods for rail tunnel deformation and disease detection usually require a large amount of equipment and manpower to achieve full section detection, which are time consuming and ine?cient. The development trend in the industry is to use laser scanning for full section detection. In this paper, a design scheme for a tunnel monitoring and measuring system with laser scanning as the main sensor for tunnel environmental disease and deformation analysis is proposed. The system provides functions such as tunnel point cloud collection, section deformation analysis, dislocation analysis, disease extraction, tunnel and track image generation, roaming video generation, etc. Field engineering indicated that the repeatability of the convergence diameter detection of the system can reach ±2 mm, dislocation repeatability can reach ±3 mm, the image resolution is about 0.5 mm/pixel in the ballast part, and the resolution of the inner wall of the tunnel is about 1.5 mm/pixel. The system can include human–computer interaction to extract and label diseases or appurtenances and support the generation of thematic disease maps. The developed system can provide important technical support for deformation and disease detection of rail transit tunnels.
关键词： orthophoto image,convergence diameter,disease marking,mobile laser scanning,roaming video,dislocation
更新于2025-09-16 10:30:52