scholarly journals Laser Scanning Thermography for Coating Thickness Inspection

2021 ◽  
Vol 8 (1) ◽  
pp. 17
Author(s):  
Lukas Muzika ◽  
Michal Svantner ◽  
Milan Honner ◽  
Sarka Houdkova
Keyword(s):  
Coating Thickness ◽  
Laser Scanning ◽  
Processing Technique ◽  
Surface Point ◽  
Power Laser ◽  
Ir Camera ◽  
New Approach ◽  
Pulse Thermography ◽  
Temperature Responses ◽  
Higher Sensitivity

The paper deals with a new approach to laser thermography for the inspection of coating thickness. The approach is based on scanning the specimen surface point by point, using a low-power laser, and recording the temperature responses with an IR camera. A recorded sequence is then transformed into a sequence similar to a flash pulse thermography sequence. Fast Fourier transform was used as a processing technique. The results are compared with a flash pulse thermography measurement. It was shown that the laser thermography measurement provides a higher sensitivity to thickness changes than flash pulse thermography measurement.

scholarly journals Expressway Surface Point Extraction from Mobile Laser Scanning Point Clouds

2013 ◽  
Vol 6 (2) ◽  
pp. 15-19 ◽  
Author(s):  
Rufei Liu ◽  
◽  
Maoyi Tian ◽  
Bo Shi ◽  
Junyi Xu ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Point Clouds ◽  
Surface Point

scholarly journals Development of Image Processing for Crack Detection on Concrete Structures through Terrestrial Laser Scanning Associated with the Octree Structure

2018 ◽  
Vol 8 (12) ◽  
pp. 2373 ◽  
Author(s):  
Soojin Cho ◽  
Seunghee Park ◽  
Gichun Cha ◽  
Taekeun Oh
Keyword(s):  
Image Processing ◽  
Laser Scanning ◽  
Crack Detection ◽  
Surface Condition ◽  
Terrestrial Laser Scanning ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Morphological Operations ◽  
Cloud Data ◽  
Remote Sensing Technique

Terrestrial laser scanning (TLS) provides a rapid remote sensing technique to model 3D objects but can also be used to assess the surface condition of structures. In this study, an effective image processing technique is proposed for crack detection on images extracted from the octree structure of TLS data. To efficiently utilize TLS for the surface condition assessment of large structures, a process was constructed to compress the original scanned data based on the octree structure. The point cloud data obtained by TLS was converted into voxel data, and further converted into an octree data structure, which significantly reduced the data size but minimized the loss of resolution to detect cracks on the surface. The compressed data was then used to detect cracks on the surface using a combination of image processing algorithms. The crack detection procedure involved the following main steps: (1) classification of an image into three categories (i.e., background, structural joints and sediments, and surface) using K-means clustering according to color similarity, (2) deletion of non-crack parts on the surface using improved subtraction combined with median filtering and K-means clustering results, (3) detection of major crack objects on the surface based on Otsu’s binarization method, and (4) highlighting crack objects by morphological operations. The proposed technique was validated on a spillway wall of a concrete dam structure in South Korea. The scanned data was compressed up to 50% of the original scanned data, while showing good performance in detecting cracks with various shapes.

scholarly journals Reduction Method for Mobile Laser Scanning Data

2018 ◽  
Vol 7 (7) ◽  
pp. 285 ◽  
Author(s):  
Wioleta Błaszczak-Bąk ◽  
Zoltan Koppanyi ◽  
Charles Toth
Keyword(s):  
Data Reduction ◽  
Point Cloud ◽  
Laser Scanning ◽  
Digital Terrain Model ◽  
New Approach ◽  
Terrain Model ◽  
Digital Terrain ◽  
Airborne Laser ◽  
Short Time ◽  
Mls Method

Mobile Laser Scanning (MLS) technology acquires a huge volume of data in a very short time. In many cases, it is reasonable to reduce the size of the dataset with eliminating points in such a way that the datasets, after reduction, meet specific optimization criteria. Various methods exist to decrease the size of point cloud, such as raw data reduction, Digital Terrain Model (DTM) generalization or generation of regular grid. These methods have been successfully applied on data captured from Airborne Laser Scanning (ALS) and Terrestrial Laser Scanning (TLS), however, they have not been fully analyzed on data captured by an MLS system. The paper presents our new approach, called the Optimum Single MLS Dataset method (OptD-single-MLS), which is an algorithm for MLS data reduction. The tests were carried out in two variants: (1) for raw sensory measurements and (2) for a georeferenced 3D point cloud. We found that the OptD-single-MLS method provides a good solution in both variants; therefore, the choice of the reduction variant depends only on the user.

Effect of Laser Transformation Hardening on the Accuracy of SPIF Formed Parts

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Amirahmad Mohammadi ◽  
Hans Vanhove ◽  
Albert Van Bael ◽  
Marc Seefeldt ◽  
Joost R. Duflou
Keyword(s):  
Laser Scanning ◽  
Incremental Forming ◽  
Single Point ◽  
Microstructural Analysis ◽  
Field Measurements ◽  
Single Point Incremental Forming ◽  
Forming Process ◽  
Ir Camera ◽  
Backing Plate ◽  
Laser Transformation Hardening

This study examines the possibility of applying lasers for the formation of laser-affected bands in hardenable steel sheets, with a specific focus on how the formation of these hardened bands can improve the accuracy of the single point incremental forming process (SPIF). For this purpose, the process parameters for the hardening process have been chosen using finite-element (FE) modeling. The results of the modeling have been validated by temperature field measurements obtained from IR camera observations. The microstructural analysis of the laser-affected zones has been performed using optical microscopy (OM) and scanning electron microscopy (SEM). These investigations confirm a phase transformation to a martensitic structure during laser scanning, and microhardness (HV0·1) results show a hardness increase by a factor of about three in the laser-affected region in comparison to that of the base metal (BM). Finally, using a laser assisted single point incremental forming (LASPIF) setup, hardened bands have been generated for preprocessing and intermediate processing during the different phases of a SPIF procedure. Geometric accuracy studies show that appropriate use of hard martensitic bands can increase the process accuracy through significantly reduction of an unwanted sheet deformation, and has the potential to eliminate the need for a backing plate.

scholarly journals Automatic detection of avalanches using a combined array classification and localization

2018 ◽  
Author(s):  
Matthias Heck ◽  
Alec van Herwijnen ◽  
Conny Hammer ◽  
Manuel Hobiger ◽  
Jürg Schweizer ◽  
...  
Keyword(s):  
Seismic Data ◽  
Markov Models ◽  
Learning Algorithm ◽  
Processing Technique ◽  
Second Step ◽  
Winter Period ◽  
Snow Avalanches ◽  
Field Site ◽  
New Approach ◽  
Training Event

Abstract. We use a seismic monitoring system to automatically determine the avalanche activity at a remote field site near Davos, Switzerland. By using a recently developed approach based on hidden Markov models (HMMs), a machine learning algorithm, we were able to automatically identify avalanches in continuous seismic data by providing as little as one single training event. Furthermore, we implemented an operational method to provide near real-time classification results. For the 2016–2017 winter period 117 events were automatically identified. False classified events such as airplanes and local earthquakes were filtered using a new approach containing two additional classification steps. In a first step, we implemented a second HMM based classifier at a second array 14 km away to automatically identify airplanes and earthquakes. By cross-checking the results of both arrays we reduced the amount of false classifications by about 50 %. In a second step, we used multiple signal classifications (MUSIC), an array processing technique to determine the direction of the source. Although avalanche events have a moving source character only small changes of the source direction are common for snow avalanches whereas false classifications had large changes in the source direction and were therefore dismissed. From the 117 detected events during the 4 month period we were able to identify 90 false classifications based on these two additional steps. The obtained avalanche activity based on the remaining 27 avalanche events was in line with visual observations performed in the area of Davos.

scholarly journals A Multipurpose Image Processing Technique for Wireless and Wired Networks

2012 ◽  
pp. 205-209
Author(s):  
Akash Kumar Bhoi ◽  
Baidyanath Panda
Keyword(s):  
Image Processing ◽  
Communication Network ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Single Server ◽  
Receiver Side ◽  
High Quality ◽  
New Approach ◽  
Wired Networks ◽  
Prime Problem

One of the most important and challenging goal of current and future communication network is transmission of high quality images from sender to receiver side quickly with least error where limitation of bandwidth is a prime problem. Here we will discuss a new approach towards compressing and decompressing with perfect accuracy for its suitable transmission and reception. This technology is also helpful in Server and Client models used in industries where a large number of clients work over a single Server. Hence to minimize the load during transmission of a volumetric image/video this process can be implemented.

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