Automatic segmentation of individual particles from a terrestrial laser scanning point cloud of a mountain river bed

The fluvial transport is an important aspect of hydrological and geomorphologic studies. The knowledge about the movement parameters of different-size fractions is essential in many applications, such as the exploration of the watercourse changes, the calculation of the river bed parameters or the investigation of the frequency and the nature of the weather events. Traditional techniques used for the fluvial transport investigations do not provide any information about the long-term horizontal movement of the rocks. This information can be gained by means of terrestrial laser scanning (TLS). However, this is a complex issue consisting of several stages of data processing. In this study the methodology for individual rocks segmentation from TLS point cloud has been proposed, which is the first step for the semi-automatic algorithm for movement detection of individual rocks. The proposed algorithm is executed in two steps. Firstly, the point cloud is classified as rocks or background using only geometrical information. Secondly, the DBSCAN algorithm is executed iteratively on points classified as rocks until only one stone is detected in each segment. The number of rocks in each segment is determined using principal component analysis (PCA) and simple derivative method for peak detection. As a result, several segments that correspond to individual rocks are formed. Numerical tests were executed on two test samples. The results of the semi-automatic segmentation were compared to results acquired by manual segmentation. The proposed methodology enabled to successfully segment 76&thinsp;% and 72&thinsp;% of rocks in the test sample 1 and test sample 2, respectively.

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MONITORING OF FLUVIAL TRANSPORT IN THE MOUNTAIN RIVER BED USING TERRESTRIAL LASER SCANNING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b7-523-2016 ◽

2016 ◽

Vol XLI-B7 ◽

pp. 523-528

Author(s):

G. Jozkow ◽

A. Borkowski ◽

M. Kasprzak

Keyword(s):

Laser Scanning ◽

River Flow ◽

Terrestrial Laser Scanning ◽

Point Clouds ◽

Major Axis ◽

Strong Impact ◽

Mountain River ◽

Mountain Areas ◽

Fluvial Transport ◽

River Bed

The fluvial transport is the surface process that has a strong impact on the topography changes, especially in mountain areas. Traditional hydrological measurements usually give a good understanding of the river flow, however, the information of the bedload movement in the rivers is still insufficient. In particular, there is limited knowledge about the movement of the largest clasts, i.e. boulders. This investigation addresses mentioned issues by employing Terrestrial Laser Scanning (TLS) to monitor annual changes of the mountain river bed. The vertical changes were estimated based on the Digital Elevation Model (DEM) of difference (DoD) while transported boulders were identified based on the distances between point clouds and RGB-coloured points. Combined RGB point clouds allowed also to measure 3D displacements of boulders. The results showed that the highest dynamic of the fluvial process occurred between years 2012-2013. Obtained DoD clearly indicated alternating zones of erosion and deposition of the sediment finer fractions in the local sedimentary traps. The horizontal displacement of the rock material in the river bed showed high complexity resulting in the displacement of large boulders (major axis about 0.8 m) for the distance up to 2.3 m.

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MONITORING OF FLUVIAL TRANSPORT IN THE MOUNTAIN RIVER BED USING TERRESTRIAL LASER SCANNING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b7-523-2016 ◽

2016 ◽

Vol XLI-B7 ◽

pp. 523-528 ◽

Cited By ~ 1

Author(s):

G. Jozkow ◽

A. Borkowski ◽

M. Kasprzak

Keyword(s):

Laser Scanning ◽

River Flow ◽

Terrestrial Laser Scanning ◽

Point Clouds ◽

Major Axis ◽

Strong Impact ◽

Mountain River ◽

Mountain Areas ◽

Fluvial Transport ◽

River Bed

The fluvial transport is the surface process that has a strong impact on the topography changes, especially in mountain areas. Traditional hydrological measurements usually give a good understanding of the river flow, however, the information of the bedload movement in the rivers is still insufficient. In particular, there is limited knowledge about the movement of the largest clasts, i.e. boulders. This investigation addresses mentioned issues by employing Terrestrial Laser Scanning (TLS) to monitor annual changes of the mountain river bed. The vertical changes were estimated based on the Digital Elevation Model (DEM) of difference (DoD) while transported boulders were identified based on the distances between point clouds and RGB-coloured points. Combined RGB point clouds allowed also to measure 3D displacements of boulders. The results showed that the highest dynamic of the fluvial process occurred between years 2012-2013. Obtained DoD clearly indicated alternating zones of erosion and deposition of the sediment finer fractions in the local sedimentary traps. The horizontal displacement of the rock material in the river bed showed high complexity resulting in the displacement of large boulders (major axis about 0.8 m) for the distance up to 2.3 m.

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Assessment of automatic segmentation accuracy with various point cloud density

Geodesy and Cartography ◽

10.22389/0016-7126-2020-961-7-47-55 ◽

2020 ◽

Vol 961 (7) ◽

pp. 47-55

Author(s):

A.G. Yunusov ◽

A.J. Jdeed ◽

N.S. Begliarov ◽

M.A. Elshewy

Keyword(s):

Point Cloud ◽

Laser Scanning ◽

Reference Data ◽

Automatic Segmentation ◽

Geometric Accuracy ◽

Segmentation Method ◽

Segmentation Methods ◽

Segmentation Accuracy ◽

Number Of Segments ◽

Cloud Density

Laser scanning is considered as one of the most useful and fast technologies for modelling. On the other hand, the size of scan results can vary from hundreds to several million points. As a result, the large volume of the obtained clouds leads to complication at processing the results and increases the time costs. One way to reduce the volume of a point cloud is segmentation, which reduces the amount of data from several million points to a limited number of segments. In this article, we evaluated effect on the performance, the accuracy of various segmentation methods and the geometric accuracy of the obtained models at density changes taking into account the processing time. The results of our experiment were compared with reference data in a form of comparative analysis. As a conclusion, some recommendations for choosing the best segmentation method were proposed.

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Revealing Changes in the Stem Form and Volume Allocation in Diverse Boreal Forests Using Two-Date Terrestrial Laser Scanning

Forests ◽

10.3390/f12070835 ◽

2021 ◽

Vol 12 (7) ◽

pp. 835

Author(s):

Ville Luoma ◽

Tuomas Yrttimaa ◽

Ville Kankare ◽

Ninni Saarinen ◽

Jiri Pyörälä ◽

...

Keyword(s):

Tree Growth ◽

Point Cloud ◽

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Point Clouds ◽

Stem Volume ◽

Accurate Information ◽

Stem Form ◽

Monitoring Period ◽

Significant Difference

Tree growth is a multidimensional process that is affected by several factors. There is a continuous demand for improved information on tree growth and the ecological traits controlling it. This study aims at providing new approaches to improve ecological understanding of tree growth by the means of terrestrial laser scanning (TLS). Changes in tree stem form and stem volume allocation were investigated during a five-year monitoring period. In total, a selection of attributes from 736 trees from 37 sample plots representing different forest structures were extracted from taper curves derived from two-date TLS point clouds. The results of this study showed the capability of point cloud-based methods in detecting changes in the stem form and volume allocation. In addition, the results showed a significant difference between different forest structures in how relative stem volume and logwood volume increased during the monitoring period. Along with contributing to providing more accurate information for monitoring purposes in general, the findings of this study showed the ability and many possibilities of point cloud-based method to characterize changes in living organisms in particular, which further promote the feasibility of using point clouds as an observation method also in ecological studies.

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THE USING OF TERRESTRIAL LASER (POINT CLOUD) SCANNING TECHNOLOGIES ON URBAN SCALE: EXAMPLE OF THE HISTORICAL URBAN TEXTURE OF LAPSEKİ

INTERNATIONAL REFEREED JOURNAL OF DESIGN AND ARCHITECTURE ◽

10.17365/tmd.2021.turkey.23.03 ◽

2021 ◽

Vol 0 (23) ◽

pp. 0-0

Author(s):

Hatice Çiğdem ZAĞRA ◽

Sibel ÖZDEN

Keyword(s):

Point Cloud ◽

Laser Scanning ◽

Three Dimensional ◽

Terrestrial Laser Scanning ◽

Traditional Methods ◽

Life Project ◽

Three Dimensional Models ◽

Architectural Restoration ◽

Cloud Technologies ◽

Orthophoto Images

Aim: This study aims to comparatively evaluate the use potential of orthophoto images obtained by terrestrial laser scanning technologies on an urban scale through the "Old Lapseki Finds Life Project" prepared using terrestrial laser scanning technologies and the "Enez Historical City Square Project" prepared using traditional methods. Method: In the study, street improvement projects of 29.210 m2 Lapseki and 29.214 m2 Enez city designed on an urban scale were evaluated and compared with descriptive statistics based on different parameters. Results: In the study, it has been determined that terrestrial laser (point cloud) technologies are 99,9% accurate when compared to traditional methods, save time by 83,08% and reduce workforce by 80%. In addition, it has been determined that terrestrial laser scanning technologies accelerate project processes compared to traditional methods. Conclusion: In this study, the use of laser scanning technologies, which are basically reverse engineering applications, in architectural restoration projects, determination of the current situation and damage, architectural documentation of structures and preparation of three-dimensional models, in terms of efficiency in survey studies are evaluated. It has been observed that orthophoto images obtained by terrestrial laser scanning technologies in architectural relief-restoration-restitution projects have potentials' worth using in different stages of the project.

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Network method for deformation analysis of three-dimensional point cloud with terrestrial laser scanning sensor

International Journal of Distributed Sensor Networks ◽

10.1177/1550147718814139 ◽

2018 ◽

Vol 14 (11) ◽

pp. 155014771881413 ◽

Cited By ~ 8

Author(s):

Xiangyang Xu ◽

Hao Yang

Keyword(s):

Point Cloud ◽

Laser Scanning ◽

Three Dimensional ◽

Terrestrial Laser Scanning ◽

Deformation Analysis ◽

Transverse Displacement ◽

Displacement Analysis ◽

Accuracy Measurement ◽

Network Method ◽

Displacement Information

The complexity of structural materials is increasing the importance of the technology for high accuracy measurement. How to obtain the displacement information of structural feature points accurately and efficiently is the key issue of deformation analysis. In this article, displacement analysis of a composite arched structure is investigated based on the terrestrial laser scanning technique. A new method based on the measured point cloud is proposed to analyze the displacement of surficial points, resulting in not only the displacement size but also the displacement direction. The innovation lies in extracting the displacement information with a network and remapped point cloud, which is called the network method. The displacement map obtained demonstrates that the transverse displacement in the experiment plays an important role in the safety of the structure, which could not be observed and obtained by the surface approximation method. Therefore, the panorama- and pointwise displacement analysis technologies contribute to ensure the safety of increasingly complex constructions.

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