3D Filtering of High-Resolution Terrestrial Laser Scanner Point Clouds for Cultural Heritage Documentation

Nowadays, one of the techniques more used for documentation of cultural heritage is terrestrial laser scanner (TLS). This kind of instrumental has become essential in this kind of heritage projects. However, in many projects, the captured information by these systems are excessive, which hinders its data processing and information extraction. But when the documentation purpose is limited to the visualization or dissemination, the final products can be simpler than those obtained from the dense point clouds and the resulting detailed models. In this paper it is presented an approach based on TLS data processed with spherical images algorithms. TLS point clouds are used to simulate spherical images allowing the storage, processing, visualization and dissemination of both data and products. This approach has been applied to a real study case in the documentation of the chapterhouse of the Cathedral of Jaén.

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Fitting Terrestrial Laser Scanner Point Clouds with T-Splines: Local Refinement Strategy for Rigid Body Motion

Remote Sensing ◽

10.3390/rs13132494 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2494

Author(s):

Gaël Kermarrec ◽

Niklas Schild ◽

Jan Hartmann

Keyword(s):

Point Cloud ◽

Goodness Of Fit ◽

Laser Scanner ◽

Point Clouds ◽

Statistical Testing ◽

Computational Time ◽

Terrestrial Laser Scanner ◽

Reference Surface ◽

Local Refinement ◽

Surface Approximation

T-splines have recently been introduced to represent objects of arbitrary shapes using a smaller number of control points than the conventional non-uniform rational B-splines (NURBS) or B-spline representatizons in computer-aided design, computer graphics and reverse engineering. They are flexible in representing complex surface shapes and economic in terms of parameters as they enable local refinement. This property is a great advantage when dense, scattered and noisy point clouds are approximated using least squares fitting, such as those from a terrestrial laser scanner (TLS). Unfortunately, when it comes to assessing the goodness of fit of the surface approximation with a real dataset, only a noisy point cloud can be approximated: (i) a low root mean squared error (RMSE) can be linked with an overfitting, i.e., a fitting of the noise, and should be correspondingly avoided, and (ii) a high RMSE is synonymous with a lack of details. To address the challenge of judging the approximation, the reference surface should be entirely known: this can be solved by printing a mathematically defined T-splines reference surface in three dimensions (3D) and modeling the artefacts induced by the 3D printing. Once scanned under different configurations, it is possible to assess the goodness of fit of the approximation for a noisy and potentially gappy point cloud and compare it with the traditional but less flexible NURBS. The advantages of T-splines local refinement open the door for further applications within a geodetic context such as rigorous statistical testing of deformation. Two different scans from a slightly deformed object were approximated; we found that more than 40% of the computational time could be saved without affecting the goodness of fit of the surface approximation by using the same mesh for the two epochs.

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Comparison of Depth Camera and Terrestrial Laser Scanner in Monitoring Structural Deflections

Sensors ◽

10.3390/s21010201 ◽

2020 ◽

Vol 21 (1) ◽

pp. 201

Author(s):

Michael Bekele Maru ◽

Donghwan Lee ◽

Kassahun Demissie Tola ◽

Seunghee Park

Keyword(s):

Optical Sensors ◽

Point Cloud ◽

Three Dimensional ◽

Laser Scanner ◽

Point Clouds ◽

Depth Camera ◽

Terrestrial Laser Scanner ◽

Cloud Data ◽

3D Point Clouds ◽

3D Information

Modeling a structure in the virtual world using three-dimensional (3D) information enhances our understanding, while also aiding in the visualization, of how a structure reacts to any disturbance. Generally, 3D point clouds are used for determining structural behavioral changes. Light detection and ranging (LiDAR) is one of the crucial ways by which a 3D point cloud dataset can be generated. Additionally, 3D cameras are commonly used to develop a point cloud containing many points on the external surface of an object around it. The main objective of this study was to compare the performance of optical sensors, namely a depth camera (DC) and terrestrial laser scanner (TLS) in estimating structural deflection. We also utilized bilateral filtering techniques, which are commonly used in image processing, on the point cloud data for enhancing their accuracy and increasing the application prospects of these sensors in structure health monitoring. The results from these sensors were validated by comparing them with the outputs from a linear variable differential transformer sensor, which was mounted on the beam during an indoor experiment. The results showed that the datasets obtained from both the sensors were acceptable for nominal deflections of 3 mm and above because the error range was less than ±10%. However, the result obtained from the TLS were better than those obtained from the DC.

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Explanation for the seam line discontinuity in terrestrial laser scanner point clouds

ISPRS Journal of Photogrammetry and Remote Sensing ◽

10.1016/j.isprsjprs.2019.05.012 ◽

2019 ◽

Vol 154 ◽

pp. 59-69 ◽

Cited By ~ 2

Author(s):

D.D. Lichti ◽

C.L. Glennie ◽

K. Al-Durgham ◽

A. Jahraus ◽

J. Steward

Keyword(s):

Laser Scanner ◽

Point Clouds ◽

Terrestrial Laser Scanner

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3D Digital Documentation of a Cultural Heritage Site Using Terrestrial Laser Scanner—A Case Study

Lecture Notes in Civil Engineering - Applications of Geomatics in Civil Engineering ◽

10.1007/978-981-13-7067-0_3 ◽

2019 ◽

pp. 49-58 ◽

Cited By ~ 2

Author(s):

S. K. P. Kushwaha ◽

Karun Reuel Dayal ◽

Sachchidanand ◽

S. Raghavendra ◽

Hina Pande ◽

...

Keyword(s):

Cultural Heritage ◽

Laser Scanner ◽

Terrestrial Laser Scanner ◽

Heritage Site ◽

Digital Documentation

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The first terrestrial laser scanner application over Vesuvius: High resolution model of a volcano crater

International Journal of Remote Sensing ◽

10.1080/01431160500534473 ◽

2007 ◽

Vol 28 (1) ◽

pp. 203-219 ◽

Cited By ~ 19

Author(s):

A. Pesci ◽

F. Loddo ◽

D. Conforti

Keyword(s):

High Resolution ◽

Laser Scanner ◽

Terrestrial Laser Scanner ◽

Resolution Model ◽

High Resolution Model

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Displacement Study of a Large-Scale Freeform Timber Plate Structure Using a Total Station and a Terrestrial Laser Scanner

Sensors ◽

10.3390/s20020413 ◽

2020 ◽

Vol 20 (2) ◽

pp. 413 ◽

Cited By ~ 1

Author(s):

Anh Chi Nguyen ◽

Yves Weinand

Keyword(s):

Large Scale ◽

Numerical Models ◽

Laser Scanner ◽

Experimental Tests ◽

Point Clouds ◽

Element Model ◽

Experimental Investigations ◽

Bottom Surface ◽

Terrestrial Laser Scanner ◽

Total Station

Recent advances in timber construction have led to the realization of complex timber plate structures assembled with wood-wood connections. Although advanced numerical modelling tools have been developed to perform their structural analysis, limited experimental tests have been carried out on large-scale structures. However, experimental investigations remain necessary to better understand their mechanical behaviour and assess the numerical models developed. In this paper, static loading tests performed on timber plate shells of about 25 m span are reported. Displacements were measured at 16 target positions on the structure using a total station and on its entire bottom surface using a terrestrial laser scanner. Both methods were compared to each other and to a finite element model in which the semi-rigidity of the connections was represented by springs. Total station measurements provided more consistent results than point clouds, which nonetheless allowed the visualization of displacement fields. Results predicted by the model were found to be in good agreement with the measurements compared to a rigid model. The semi-rigid behaviour of the connections was therefore proven to be crucial to precisely predict the behaviour of the structure. Furthermore, large variations were observed between as-built and designed geometries due to the accumulation of fabrication and construction tolerances.

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Robust external calibration of terrestrial laser scanner and digital camera for structural monitoring

Journal of Applied Geodesy ◽

10.1515/jag-2018-0038 ◽

2019 ◽

Vol 13 (2) ◽

pp. 105-134 ◽

Cited By ~ 2

Author(s):

Mohammad Omidalizarandi ◽

Boris Kargoll ◽

Jens-André Paffenholz ◽

Ingo Neumann

Keyword(s):

Em Algorithm ◽

Laser Scanner ◽

Digital Camera ◽

Point Clouds ◽

Deformation Monitoring ◽

Deformation Analysis ◽

Terrestrial Laser Scanner ◽

External Calibration ◽

3D Point Clouds ◽

Calibration Parameters

Abstract In the last two decades, the integration of a terrestrial laser scanner (TLS) and digital photogrammetry, besides other sensors integration, has received considerable attention for deformation monitoring of natural or man-made structures. Typically, a TLS is used for an area-based deformation analysis. A high-resolution digital camera may be attached on top of the TLS to increase the accuracy and completeness of deformation analysis by optimally combining points or line features extracted both from three-dimensional (3D) point clouds and captured images at different epochs of time. For this purpose, the external calibration parameters between the TLS and digital camera needs to be determined precisely. The camera calibration and internal TLS calibration are commonly carried out in advance in the laboratory environments. The focus of this research is to highly accurately and robustly estimate the external calibration parameters between the fused sensors using signalised target points. The observables are the image measurements, the 3D point clouds, and the horizontal angle reading of a TLS. In addition, laser tracker observations are used for the purpose of validation. The functional models are determined based on the space resection in photogrammetry using the collinearity condition equations, the 3D Helmert transformation and the constraint equation, which are solved in a rigorous bundle adjustment procedure. Three different adjustment procedures are developed and implemented: (1) an expectation maximization (EM) algorithm to solve a Gauss-Helmert model (GHM) with grouped t-distributed random deviations, (2) a novel EM algorithm to solve a corresponding quasi-Gauss-Markov model (qGMM) with t-distributed pseudo-misclosures, and (3) a classical least-squares procedure to solve the GHM with variance components and outlier removal. The comparison of the results demonstrates the precise, reliable, accurate and robust estimation of the parameters in particular by the second and third procedures in comparison to the first one. In addition, the results show that the second procedure is computationally more efficient than the other two.

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LiDAR derived high resolution topography: the next challenge for the analysis of terraces stability and vineyard soil erosion

Journal of Agricultural Engineering ◽

10.4081/jae.2013.258 ◽

2013 ◽

Vol 44 (2s) ◽

Cited By ~ 5

Author(s):

Federico Preti ◽

Paolo Tarolli ◽

Andrea Dani ◽

Simone Calligaro ◽

Massimo Prosdocimi

Keyword(s):

High Resolution ◽

Soil Erosion ◽

Slope Failure ◽

Flow Direction ◽

Laser Scanner ◽

Airborne Lidar ◽

Wall Structure ◽

Terrestrial Laser Scanner ◽

Erosion Risk ◽

Soil Erosion Risk

The soil erosion in the vineyards is a critical issue that could affect their productivity, but also, when the cultivation is organized in terraces, increase the risk due to derived slope failure processes. If terraces are not correctly designed or maintained, a progressively increasing of gully erosion affects the structure of the walls. The results of this process is the increasing of connectivity and runoff. In order to overcome such issues it is really important to recognize in detail all the surface drainage paths, thus providing a basis upon which develop a suitable drainage system or provide structural measures for the soil erosion risk mitigation. In the last few years, the airborne LiDAR technology led to a dramatic increase in terrain information. Airborne LiDAR and Terrestrial Laser Scanner derived high-resolution Digital Terrain Models (DTMs) have opened avenues for hydrologic and geomorphologic studies (Tarolli et al., 2009). In general, all the main surface process signatures are correctly recognized using a DTM with cell sizes of 1 m. However sub-meter grid sizes may be more suitable in those situations where the analysis of micro topography related to micro changes is critical for slope failures risk assessment or for the design of detailed drainage flow paths. The Terrestrial Laser Scanner (TLS) has been proven to be an useful tool for such detailed field survey. In this work, we test the effectiveness of high resolution topography derived by airborne LiDAR and TLS for the recognition of areas subject to soil erosion risk in a typical terraced vineyard landscape of “Chianti Classico” (Tuscany, Italy). The algorithm proposed by Tarolli et al. (2013), for the automatic recognition of anthropic feature induced flow direction changes, has been tested. The results underline the effectiveness of LiDAR and TLS data in the analysis of soil erosion signatures in vineyards, and indicate the high resolution topography as a useful tool to improve the land use management of such areas. The stability conditions have been analyzed under the influence of the measured geometry alterations of the wall structure.

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