scholarly journals COMPARISON OF TARGET- AND MUTUAL INFORMATON BASED CALIBRATION OF TERRESTRIAL LASER SCANNER AND DIGITAL CAMERA FOR DEFORMATION MONITORING

2015 ◽  
Vol XL-1-W5 ◽  
pp. 559-564 ◽  
Author(s):  
M. Omidalizarandi ◽  
I. Neumann
Keyword(s):  
Laser Scanner ◽  
Digital Camera ◽  
Deformation Monitoring ◽  
Sensor System ◽  
Deformation Analysis ◽  
Accurate Estimation ◽  
Terrestrial Laser Scanner ◽  
Ongoing Research ◽  
Extrinsic Calibration ◽  
Advantages And Disadvantages

In the current state-of-the-art, geodetic deformation analysis of natural and artificial objects (e.g. dams, bridges,...) is an ongoing research in both static and kinematic mode and has received considerable interest by researchers and geodetic engineers. In this work, due to increasing the accuracy of geodetic deformation analysis, a terrestrial laser scanner (TLS; here the Zoller+Fröhlich IMAGER 5006) and a high resolution digital camera (Nikon D750) are integrated to complementarily benefit from each other. In order to optimally combine the acquired data of the hybrid sensor system, a highly accurate estimation of the extrinsic calibration parameters between TLS and digital camera is a vital preliminary step. Thus, the calibration of the aforementioned hybrid sensor system can be separated into three single calibrations: calibration of the camera, calibration of the TLS and extrinsic calibration between TLS and digital camera. In this research, we focus on highly accurate estimating extrinsic parameters between fused sensors and target- and targetless (mutual information) based methods are applied. In target-based calibration, different types of observations (image coordinates, TLS measurements and laser tracker measurements for validation) are utilized and variance component estimation is applied to optimally assign adequate weights to the observations. Space resection bundle adjustment based on the collinearity equations is solved using Gauss-Markov and Gauss-Helmert model. Statistical tests are performed to discard outliers and large residuals in the adjustment procedure. At the end, the two aforementioned approaches are compared and advantages and disadvantages of them are investigated and numerical results are presented and discussed.

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

2019 ◽  
Vol 13 (2) ◽  
pp. 105-134 ◽  
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.

The Horizontal Deformation Analysis of High-rise Buildings

2017 ◽  
Author(s):  
Žymantas Gražulis ◽  
Boleslovas Krikštaponis ◽  
Algirdas Neseckas ◽  
Darius Popovas ◽  
Raimundas Putrimas ◽  
...  
Keyword(s):  
Power Plants ◽  
Laser Scanning ◽  
Thermal Power ◽  
Laser Scanner ◽  
Deformation Analysis ◽  
Terrestrial Laser Scanner ◽  
Horizontal Deformation ◽  
Cloud Data ◽  
High Rise ◽  
Cloud Data Processing

The horizontal deformation analysis of high-rise buildings, quite often is complicated because buildings like chimneys, towers and etc, have complex and asymmetric shapes, consequently there is not always the possibility to apply the method of single points motion analysis. Furthermore, the horizontal deformation analysis is complicated using standard measurement methods like measurements with electronic total stations or optical theodolites. In such case the terrestrial laser scanner could be superior to traditional measurements. However, the terrestrial laser scanner still not widely used to survey building horizontal deformations using high precision measurements. The main aim of this work is to determine the suitability to measure deflections of buildings from the vertical using terrestrial laser scanners and to investigate point cloud data processing. Measurements of horizontal deformation were carried out using the over ground laser scanner and electronic total station. Horizontal deformations of chimneys of thermal power plants were investigated using corresponding methods. Deformation indicators and evaluated measurement accuracies between different methods were compared. Data analysis of terrestrial laser scanning is more complex, time consuming and requires sophisticated hardware resources in comparison with the traditional methods, however results are much more detailed and informative.

scholarly journals Freeze/Thaw-Induced Deformation Monitoring and Assessment of the Slope in Permafrost Based on Terrestrial Laser Scanner and GNSS

2017 ◽  
Vol 9 (3) ◽  
pp. 198 ◽  
Author(s):  
Lihui Luo ◽  
Wei Ma ◽  
Zhongqiong Zhang ◽  
Yanli Zhuang ◽  
Yaonan Zhang ◽  
...  
Keyword(s):  
Laser Scanner ◽  
Deformation Monitoring ◽  
Terrestrial Laser Scanner ◽  
Freeze Thaw

scholarly journals PERSPECTIVE INTENSITY IMAGES FOR CO-REGISTRATION OF TERRESTRIAL LASER SCANNER AND DIGITAL CAMERA

2016 ◽  
Vol XLI-B3 ◽  
pp. 295-300
Author(s):  
Yubin Liang ◽  
Yan Qiu ◽  
Tiejun Cui
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Least Squares Method ◽  
Laser Scanner ◽  
Digital Camera ◽  
Point Clouds ◽  
Terrestrial Laser Scanner ◽  
Automatic Registration ◽  
Intensity Images ◽  
Intensity Image

Co-registration of terrestrial laser scanner and digital camera has been an important topic of research, since reconstruction of visually appealing and measurable models of the scanned objects can be achieved by using both point clouds and digital images. This paper presents an approach for co-registration of terrestrial laser scanner and digital camera. A perspective intensity image of the point cloud is firstly generated by using the collinearity equation. Then corner points are extracted from the generated perspective intensity image and the camera image. The fundamental matrix F is then estimated using several interactively selected tie points and used to obtain more matches with RANSAC. The 3D coordinates of all the matched tie points are directly obtained or estimated using the least squares method. The robustness and effectiveness of the presented methodology is demonstrated by the experimental results. Methods presented in this work may also be used for automatic registration of terrestrial laser scanning point clouds.

scholarly journals TERRAIN EXTRACTION BY INTEGRATING TERRESTRIAL LASER SCANNER DATA AND SPECTRAL INFORMATION

2015 ◽  
Vol XL-2/W4 ◽  
pp. 45-51 ◽  
Author(s):  
C. L. Lau ◽  
S. Halim ◽  
M. Zulkepli ◽  
A. M. Azwan ◽  
W. L. Tang ◽  
...  
Keyword(s):  
Point Cloud ◽  
Laser Scanner ◽  
Digital Camera ◽  
Digital Terrain Model ◽  
Point Clouds ◽  
Spectral Information ◽  
Terrestrial Laser Scanner ◽  
Cloud Data ◽  
Terrain Model ◽  
Colour Image

The extraction of true terrain points from unstructured laser point cloud data is an important process in order to produce an accurate digital terrain model (DTM). However, most of these spatial filtering methods just utilizing the geometrical data to discriminate the terrain points from nonterrain points. The point cloud filtering method also can be improved by using the spectral information available with some scanners. Therefore, the objective of this study is to investigate the effectiveness of using the three-channel (red, green and blue) of the colour image captured from built-in digital camera which is available in some Terrestrial Laser Scanner (TLS) for terrain extraction. In this study, the data acquisition was conducted at a mini replica landscape in Universiti Teknologi Malaysia (UTM), Skudai campus using Leica ScanStation C10. The spectral information of the coloured point clouds from selected sample classes are extracted for spectral analysis. The coloured point clouds which within the corresponding preset spectral threshold are identified as that specific feature point from the dataset. This process of terrain extraction is done through using developed Matlab coding. Result demonstrates that a higher spectral resolution passive image is required in order to improve the output. This is because low quality of the colour images captured by the sensor contributes to the low separability in spectral reflectance. In conclusion, this study shows that, spectral information is capable to be used as a parameter for terrain extraction.

scholarly journals 3D TEXTURED MODELLING OF BOTH EXTERIOR AND INTERIOR OF KOREAN STYLED ARCHITECTURES

2017 ◽  
Vol XLII-2/W5 ◽  
pp. 439-442 ◽  
Author(s):  
J.-D. Lee ◽  
K.-J. Bhang ◽  
W. Schuhr
Keyword(s):  
Laser Scanning ◽  
Laser Scanner ◽  
3D Modelling ◽  
Deformation Monitoring ◽  
Terrestrial Laser Scanner ◽  
Cultural Assets ◽  
Modelling Procedure ◽  
Digital Documentation ◽  
Documentation Tool ◽  
Safety Diagnosis

This paper describes 3D modelling procedure of two Korean styled architectures which were performed through a series of processing from data acquired with the terrestrial laser scanner. These two case projects illustate the use of terrestrial laser scanner as a digital documentation tool for management, conservation and restoration of the cultural assets. We showed an approach to automate reconstruction of both the outside and inside models of a building from laser scanning data. Laser scanning technology is much more efficient than existing photogrammetry in measuring shape and constructing spatial database for preservation and restoration of cultural assets as well as for deformation monitoring and safety diagnosis of structures.

On the use of terrestrial laser scanner for deformation analysis of the Talaga Bodas Crater West Java (Indonesia)

2016 ◽  
Author(s):  
Irwan Gumilar ◽  
Muhammad N. A. Basith ◽  
Hasanuddin Z. Abidin ◽  
Nia Haerani
Keyword(s):  
Laser Scanner ◽  
Deformation Analysis ◽  
Terrestrial Laser Scanner ◽  
West Java

High accuracy calibration of installation parameters between 3D terrestrial laser scanner and external-installed digital camera

2016 ◽  
Vol 24 (9) ◽  
pp. 2158-2166 ◽  
Author(s):  
李明磊 LI Ming-lei ◽  
高欣圆 GAO Xin-yuan ◽  
李广云 LI Guang-yun ◽  
王 力 WANG Li ◽  
刘松林 LIU Song-lin
Keyword(s):  
Laser Scanner ◽  
Digital Camera ◽  
High Accuracy ◽  
Terrestrial Laser Scanner

scholarly journals Deformation Analysis Using B-Spline Surface with Correlated Terrestrial Laser Scanner Observations—A Bridge Under Load

2020 ◽  
Vol 12 (5) ◽  
pp. 829 ◽  
Author(s):  
Gaël Kermarrec ◽  
Boris Kargoll ◽  
Hamza Alkhatib
Keyword(s):  
Laser Scanner ◽  
Point Clouds ◽  
Testing Procedure ◽  
Local Deformation ◽  
Measurement Noise ◽  
Deformation Analysis ◽  
Terrestrial Laser Scanner ◽  
B Spline ◽  
Set Up ◽  
The Impact

The choice of an appropriate metric is mandatory to perform deformation analysis between two point clouds (PC)—the distance has to be trustworthy and, simultaneously, robust against measurement noise, which may be correlated and heteroscedastic. The Hausdorff distance (HD) or its averaged derivation (AHD) are widely used to compute local distances between two PC and are implemented in nearly all commercial software. Unfortunately, they are affected by measurement noise, particularly when correlations are present. In this contribution, we focus on terrestrial laser scanner (TLS) observations and assess the impact of neglecting correlations on the distance computation when a mathematical approximation is performed. The results of the simulations are extended to real observations from a bridge under load. Highly accurate laser tracker (LT) measurements were available for this experiment: they allow the comparison of the HD and AHD between two raw PC or between their mathematical approximations regarding reference values. Based on these results, we determine which distance is better suited in the case of heteroscedastic and correlated TLS observations for local deformation analysis. Finally, we set up a novel bootstrap testing procedure for this distance when the PC are approximated with B-spline surfaces.

scholarly journals PERSPECTIVE INTENSITY IMAGES FOR CO-REGISTRATION OF TERRESTRIAL LASER SCANNER AND DIGITAL CAMERA

2016 ◽  
Vol XLI-B3 ◽  
pp. 295-300
Author(s):  
Yubin Liang ◽  
Yan Qiu ◽  
Tiejun Cui
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Least Squares Method ◽  
Laser Scanner ◽  
Digital Camera ◽  
Point Clouds ◽  
Terrestrial Laser Scanner ◽  
Automatic Registration ◽  
Intensity Images ◽  
Intensity Image

Co-registration of terrestrial laser scanner and digital camera has been an important topic of research, since reconstruction of visually appealing and measurable models of the scanned objects can be achieved by using both point clouds and digital images. This paper presents an approach for co-registration of terrestrial laser scanner and digital camera. A perspective intensity image of the point cloud is firstly generated by using the collinearity equation. Then corner points are extracted from the generated perspective intensity image and the camera image. The fundamental matrix F is then estimated using several interactively selected tie points and used to obtain more matches with RANSAC. The 3D coordinates of all the matched tie points are directly obtained or estimated using the least squares method. The robustness and effectiveness of the presented methodology is demonstrated by the experimental results. Methods presented in this work may also be used for automatic registration of terrestrial laser scanning point clouds.

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