scholarly journals A study on setting the control point for shape measurement of a wooden check dam using a terrestrial laser scanner

2020 ◽  
Vol 46 (1) ◽  
pp. 79-82
Author(s):  
Yasuhiro OGAWA ◽  
Koji TAMAI ◽  
Wataru MURAKAMI ◽  
Takashi OKAMOTO ◽  
Yasuhiko OKADA
Keyword(s):  
Control Point ◽  
Laser Scanner ◽  
Shape Measurement ◽  
Terrestrial Laser Scanner ◽  
Check Dam

INVESTIGATIONS OF THE BALTIC SEA COASTAL ZONE ABOVE-WATER PART TOPOGRAPHY DYNAMICS BY MEANS OF TERRESTRIAL LASER SCANNER (SVETLOGORSK CITY, KALININGRAD REGION)

2017 ◽  
Author(s):  
Nikolay Lugovoy ◽  
Nikolay Lugovoy ◽  
Askar Ilyasov ◽  
Askar Ilyasov ◽  
Elena Pronina ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Coastal Zone ◽  
Coastal Erosion ◽  
Laser Scanner ◽  
Terrestrial Laser Scanner ◽  
The Baltic Sea ◽  
Coastal Dynamics ◽  
Kaliningrad Region ◽  
The Baltic

The paper describes application of the terrestrial laser scanner for investigation of coastal dynamics of the Svetlogorskaya Bay, Baltic Sea. Methods of investigation and results of surveys repeated over the two consecutive years for quantification of coastal erosion and slope processes within the coastal zone are presented.

INSIGHTS FROM REPEATED TERRESTRIAL LASER-SCANNER SURVEYS OF CHANNEL-WALL EROSION ALONG THE SOUTH RIVER, VIRGINIA

2020 ◽  
Author(s):  
Collin Megee ◽  
◽  
Michael O'Neal ◽  
Joseph Clemens ◽  
Erica McMaster ◽  
...  
Keyword(s):  
Channel Wall ◽  
Laser Scanner ◽  
Terrestrial Laser Scanner ◽  
The South

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

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.

scholarly journals Direct Assessment of Biomass Productivity in Short Rotation Forestry (SRF) with the Terrestrial Laser Scanner (TLS). Case of Study in NE Part of Romania (Preliminary Results)

2020 ◽  
Vol 3 (1) ◽  
pp. 93
Author(s):  
Iulian Constantin Dănilă
Keyword(s):  
Biomass Production ◽  
Laser Scanner ◽  
Biomass Productivity ◽  
Tree Height ◽  
Allometric Equations ◽  
Accurate Information ◽  
Terrestrial Laser Scanner ◽  
North East ◽  
Short Rotation ◽  
Destructive Methods

Short rotation forestry (SRF) provides an important supply of biomass for investors in this area. In the NE (North-East) part of Romania at the present time are installed over 800 Ha of this kind of crops. The SRF enjoys the support through environmental policies, in relation to climate change and the provisions of the Kyoto Protocol to reduce the concentration of CO2 in the atmosphere. A precise estimate of biomass production is necessary for the sustainable planning of forest resources and for the exchange of energy in ecosystems. The use of the terrestrial laser scanner (TLS) in estimating the production of above ground wood biomass (AGWB) of short rotation forestry (SRF) brings an important technological leap among indirect (non-destructive) methods. TLS technology is justified when destructive methods become difficult to implement, and allometric equations do not provide accurate information. The main purpose of the research is to estimate the biomass productivity on tree parts in short rotation forestry with TLS technology. Measuring the hybrid poplars crops by TLS may have the following consequences: (1) Higher accuracy of the estimate of biomass production in the SRF; (2) cost and time effective measurements over the biomass of tree parts; (3) new and validated allometric equations for SRF in NE Romania; (4) solid instrument for industry to estimate biomass. TLS technology gives accurate estimates for DBH, tree height and location, as much as the volume on segments, commercial volume or crown volume can be determined. The accuracy of these values depends on the original scan data and their co-registration. The research will contribute to the development of knowledge in the field of hybrid crops.

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

Sensors ◽  
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.

scholarly journals Assessment of Stem Volume on Plots Using Terrestrial Laser Scanner: A Precision Forestry Application

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 301
Author(s):  
Dimitrios Panagiotidis ◽  
Azadeh Abdollahnejad ◽  
Martin Slavík
Keyword(s):  
Norway Spruce ◽  
Laser Scanner ◽  
Estimation Methods ◽  
Coefficient Of Determination ◽  
Stem Volume ◽  
Small Scale ◽  
Terrestrial Laser Scanner ◽  
Precision Forestry ◽  
Total Tree ◽  
European Oak

Timber volume is an important asset, not only as an ecological component, but also as a key source of present and future revenues, which requires precise estimates. We used the Trimble TX8 survey-grade terrestrial laser scanner (TLS) to create a detailed 3D point cloud for extracting total tree height and diameter at breast height (1.3 m; DBH). We compared two different methods to accurately estimate total tree heights: the first method was based on a modified version of the local maxima algorithm for treetop detection, “HTTD”, and for the second method we used the centers of stem cross-sections at stump height (30 cm), “HTSP”. DBH was estimated by a computationally robust algebraic circle-fitting algorithm through hierarchical cluster analysis (HCA). This study aimed to assess the accuracy of these descriptors for evaluating total stem volume by comparing the results with the reference tree measurements. The difference between the estimated total stem volume from HTTD and measured stems was 2.732 m3 for European oak and 2.971 m3 for Norway spruce; differences between the estimated volume from HTSP and measured stems was 1.228 m3 and 2.006 m3 for European oak and Norway spruce, respectively. The coefficient of determination indicated a strong relationship between the measured and estimated total stem volumes from both height estimation methods with an R2 = 0.89 for HTTD and R2 = 0.87 for HTSP for European oak, and R2 = 0.98 for both HTTD and HTSP for Norway spruce. Our study has demonstrated the feasibility of finer-resolution remote sensing data for semi-automatic stem volumetric modeling of small-scale studies with high accuracy as a potential advancement in precision forestry.

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