scholarly journals Crack detection in building walls based on geometric and radiometric point cloud information

2022 ◽  
Vol 134 ◽  
pp. 104065
Author(s):  
Paulina Stałowska ◽  
Czesław Suchocki ◽  
Miłosława Rutkowska
Keyword(s):  
Point Cloud ◽  
Crack Detection ◽  
Building Walls

scholarly journals A Novel Recursive Non-Parametric DBSCAN Algorithm for 3D Data Analysis with an Application in Rockfall Detection

2021 ◽  
Vol 16 (4) ◽  
pp. 579-587
Author(s):  
Pitisit Dillon ◽  
Pakinee Aimmanee ◽  
Akihiko Wakai ◽  
Go Sato ◽  
Hoang Viet Hung ◽  
...  
Keyword(s):  
Point Cloud ◽  
Crack Detection ◽  
Spatial Clustering ◽  
Point Clouds ◽  
Divide And Conquer ◽  
Dbscan Algorithm ◽  
3D Data ◽  
Data Points ◽  
Clustering Data ◽  
Better Than

The density-based spatial clustering of applications with noise (DBSCAN) algorithm is a well-known algorithm for spatial-clustering data point clouds. It can be applied to many applications, such as crack detection, rockfall detection, and glacier movement detection. Traditional DBSCAN requires two predefined parameters. Suitable values of these parameters depend upon the distribution of the input point cloud. Therefore, estimating these parameters is challenging. This paper proposed a new version of DBSCAN that can automatically customize the parameters. The proposed method consists of two processes: initial parameter estimation based on grid analysis and DBSCAN based on the divide-and-conquer (DC-DBSCAN) approach, which repeatedly performs DBSCAN on each cluster separately and recursively. To verify the proposed method, we applied it to a 3D point cloud dataset that was used to analyze rockfall events at the Puiggcercos cliff, Spain. The total number of data points used in this study was 15,567. The experimental results show that the proposed method is better than the traditional DBSCAN in terms of purity and NMI scores. The purity scores of the proposed method and the traditional DBSCAN method were 96.22% and 91.09%, respectively. The NMI scores of the proposed method and the traditional DBSCAN method are 0.78 and 0.49, respectively. Also, it can detect events that traditional DBSCAN cannot detect.

scholarly journals TECHNIQUE OF AUTOMATIC MOBILE LASER SCANNING DATA ADJUSTMENT

2021 ◽  
Vol 26 (4) ◽  
pp. 5-23
Author(s):  
Maxim A. Altyntsev ◽  
◽  
Karkokli Hamid Majid Saber ◽  
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Control Point ◽  
Main Step ◽  
Control Points ◽  
Large Area ◽  
Road Signs ◽  
Automatic Mode ◽  
Building Walls ◽  
Data Adjustment

Adjustment is a main step in the preliminary processing of mobile laser scanning (MLS) data. As a result of this step, a point cloud is generated in a certain coordinate system. The modern software, provided with the corresponding surveying system, is capable of performing in automatic mode most stages of MLS data adjustment obtained for territories with different quantity of buildings. With a suf-ficient number of vertically arranged planar objects, such as building walls, the algorithms embedded in the software provide a high accuracy of relative adjustment, which consists in calculating and ap-plying corrections for trajectories obtained with re-scanning the same area. Absolute adjustment can also be carried out automatically, subject to the rules for placing control points in order to automatically detect them. This kind of adjustment involves transforming a point cloud with using control point coordinates measured with more accurate surveying methods. The accuracy of automatic relative adjustment can be significantly reduced with the almost complete absence of vertical flat objects. In this case, it is necessary to develop additional adjustment techniques capable of using not only flat objects of a large area, but also vertical objects, such as road signs and poles. Comprehensive technique of MLS data adjustment, which can use information on the position of road signs and poles for territories with an insufficient number of vertical flat objects is proposed. The accuracy estimation of both the relative and absolute MLS data adjustment according to the proposed technique was carried out. The choice of the required control point density for territories with different quantity of buildings is explained.

Combination of Point-Cloud Model and FCN for Dam Crack Detection and Scale Calculation

2019 ◽  
Author(s):  
Shuang Wang ◽  
Hua Zhang ◽  
Haoran Wang ◽  
Bo Chen ◽  
Yonglong Li ◽  
...  
Keyword(s):  
Point Cloud ◽  
Crack Detection ◽  
Cloud Model ◽  
Point Cloud Model

scholarly journals Comparison of Time-of-Flight and Phase-Shift TLS Intensity Data for the Diagnostics Measurements of Buildings

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 353 ◽  
Author(s):  
Czesław Suchocki
Keyword(s):  
Phase Shift ◽  
Point Cloud ◽  
Laser Scanning ◽  
Time Of Flight ◽  
Chemical Properties ◽  
Scanning System ◽  
Intensity Data ◽  
Building Walls ◽  
Multiple Samples ◽  
Laser Scanning System

In recent years, the terrestrial laser scanning system (TLS) has become one of the most popular remote and nondestructive testing (NDT) methods for diagnostic measurements of buildings and structures as well as for the assessment of architectural heritage. Apart from 3D coordinates, the power of a laser beam backscattered from the scanned object can be captured by TLS. The radiometric information of the point cloud, called “intensity”, can provide information about changes in the physio–chemical properties of the scanned surface. This intensity can be effectively used to detect defects in the surfaces of walls, such as cracks and cavities, moisture, biodeterioration (mosses and lichens) or weathered parts of the wall. Manufacturers of TLS mainly use two different principles for distance measurement, time-of-flight (TOF) and phase-shift (PS). The power of energy in both types of rangefinders might be absorbed or reflected in a slightly different way and provide more or less detailed radiometric point cloud information. The main aim of this investigation is to compare TOF and PS scanners in the context of using TLS intensity data for the diagnostics of buildings and other structures. The potential of TLS intensity data for detecting defects in building walls has been tested on multiple samples by two TOF (Riegl VZ400i, Leica ScanStation C10) and two PS (Z + F 5016 IMAGER, Faro Focus3D) scanners.

scholarly journals Aerial LiDAR Data Augmentation for Direct Point-Cloud Visualisation

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2089
Author(s):  
Ciril Bohak ◽  
Matej Slemenik ◽  
Jaka Kordež ◽  
Matija Marolt
Keyword(s):  
Point Cloud ◽  
Data Augmentation ◽  
Lidar Data ◽  
Cloud Processing ◽  
Processing Pipeline ◽  
Point Cloud Processing ◽  
Water Surfaces ◽  
Building Walls ◽  
Acquisition Technique

Direct point-cloud visualisation is a common approach for visualising large datasets of aerial terrain LiDAR scans. However, because of the limitations of the acquisition technique, such visualisations often lack the desired visual appeal and quality, mostly because certain types of objects are incomplete or entirely missing (e.g., missing water surfaces, missing building walls and missing parts of the terrain). To improve the quality of direct LiDAR point-cloud rendering, we present a point-cloud processing pipeline that uses data fusion to augment the data with additional points on water surfaces, building walls and terrain through the use of vector maps of water surfaces and building outlines. In the last step of the pipeline, we also add colour information, and calculate point normals for illumination of individual points to make the final visualisation more visually appealing. We evaluate our approach on several parts of the Slovenian LiDAR dataset.

scholarly journals Intelligent crack extraction and analysis for tunnel structures with terrestrial laser scanning measurement

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987265 ◽  
Author(s):  
Xiangyang Xu ◽  
Hao Yang
Keyword(s):  
Information Acquisition ◽  
Point Cloud ◽  
Laser Scanning ◽  
Crack Detection ◽  
Optimal Parameter ◽  
Terrestrial Laser Scanning ◽  
Crack Identification ◽  
Point Cloud Data ◽  
Cloud Data ◽  
Gaussian Filtering

An automatic and intelligent method for crack detection is significantly important, considering the popularity of large constructions. How to identify the cracks intelligently from massive point cloud data has become increasingly crucial. Terrestrial laser scanning is a measurement technique for three-dimensional information acquisition which can obtain coordinates and intensity values of the laser reflectivity of a dense point cloud quickly and accurately. In this article, we focus on the optimal parameter of Gaussian filtering to balance the efficiency of crack identification and the accuracy of crack analysis. The innovation of this article is that we propose a novel view of the signal-to-noise ratio gradient for Gaussian filtering to identify and extract the cracks automatically from the point cloud data of the terrestrial laser scanning measurement.

Effects of Vibration on the Preparation of Ultrathin Sections

1973 ◽  
Vol 31 ◽  
pp. 358-359
Author(s):  
Joseph M. Blum ◽  
Edward P. Gargiulo ◽  
J. R. Sawers
Keyword(s):  
Cutting Speed ◽  
Ground Level ◽  
Environmental Vibration ◽  
Block Face ◽  
Ultrathin Sections ◽  
Embedding Medium ◽  
Thickness Variations ◽  
Building Walls ◽  
Cutting Direction ◽  
Diamond Knife

It is now well-known that chatter (Figure 1) is caused by vibration between the microtome arm and the diamond knife. It is usually observed as a cyclical variation in “optical” density of an electron micrograph due to sample thickness variations perpendicular to the cutting direction. This vibration might be induced by using too large a block face, too large a clearance angle, excessive cutting speed, non-uniform embedding medium or microtome vibration. Another prominent cause is environmental vibration caused by inadequate building construction. Microtomes should be installed on firm, solid floors. The best floors are thick, ground-level concrete pads poured over a sand bed and isolated from the building walls. Even when these precautions are followed, we recommend an additional isolation pad placed on the top of a sturdy table.

Three-Dimensional Ultrasonic Crack Detection in Anisotropic Materials

1997 ◽  
Vol 9 (2) ◽  
pp. 59-79 ◽  
Author(s):  
J. Mattsson ◽  
A. J. Niklasson ◽  
A. Eriksson
Keyword(s):  
Crack Detection ◽  
Three Dimensional ◽  
Anisotropic Materials

Status of nondestructive control of transport function metal products at JSC EVRAZ NTMK

2020 ◽  
Vol 76 (6) ◽  
pp. 586-590
Author(s):  
S. P. Bersenev ◽  
E. M. Slobtsova
Keyword(s):  
Crack Detection ◽  
Middle Part ◽  
Control Line ◽  
Magnetic Powder ◽  
Nondestructive Control ◽  
Automated Control ◽  
Ultrasonic Control ◽  
Acoustic Contact ◽  
In Series

Achievements in the area of automated ultrasonic control of quality of rails, solid-rolled wheels and tyres, wheels magnetic powder crack detection, carried out at JSC EVRAZ NTMK. The 100% nondestructive control is accomplished by automated control in series at two ultrasonic facilities RWI-01 and four facilities УМКК-1 of magnetic powder control, installed into the exit control line in the wheel-tyre shop. Diagram of location, converters displacement and control operations in the process of control at the facility RWI-01 presented, as well as the structural diagram of the facility УМКК-1. The automated ultrasonic control of rough tyres is made in the tyres control line of the wheel-tyre shop at the facility УКБ-1Д. The facility enables to control internal defects of tyres in radial, axis and circular directions of radiation. Possibilities of the facility УКБ-1Д software were shown. Nondestructive control of railway rails is made at two facilities, comprising the automated control line of the rail and structural shop. The УКР-64Э facility of automated ultrasonic rails control is intended to reveal defects in the area of head, web and middle part of rail foot by pulse echo-method with a immersion acoustic contact. The diagram of rail P65 at the facility УКР-64Э control presented. To reveal defects of the macrostructure in the area of rail head and web by mirror-shadow method, an ultrasonic noncontact electromagnetic-acoustic facility is used. It was noted, that implementation of the 100% nondestructive control into the technology of rolled stuff production enabled to increase the quality of products supplied to customers and to increase their competiveness.

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