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Physical Sciences and Mathematics
University of Nebraska - Lincoln
Department of Construction Engineering and Management: Faculty Publications
- Keyword
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- Bridge deck (1)
- Concrete Delamination; Thermography; Laplacian of Gaussian Filter; Image Pyramid; Numerical Simulation; NDE (1)
- Concrete Delamination; Thermography; Nondestructive Evaluation; Deep Learning; Encoder-Decoder Architecture; Semantic Segmentation; UAV (1)
- Concrete Delamination; Thermography; Nondestructive Evaluation; Temperature Gradient Map; Edge-Based Level Set Function (1)
- Coverage Path Planning (1)
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- Delamination segmentation (1)
- Global threshold (1)
- Grayscale morphological reconstruction (1)
- ILIVisual inspectionPipelineDepth camera arrayCamera calibrationRoboticMotion estimateDense point-cloud model (1)
- K-means clustering (1)
- Non-uniform thermal background (1)
- Particle Swarm Optimization (1)
- Thermography (1)
- Unmanned Aerial Vehicle (1)
- Video-based Vibration Measurement; Phase-based Optical Flow; Motion Magnification; Mode Identification; Operation Deflection Shape (1)
- Viewpoint Quality (1)
Articles 1 - 7 of 7
Full-Text Articles in Engineering
Single-Pass Inline Pipeline 3d Reconstruction Using Depth Camera Array, Zhexiong Shang, Zhigang Shen
Single-Pass Inline Pipeline 3d Reconstruction Using Depth Camera Array, Zhexiong Shang, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
A novel inline inspection (ILI) approach using depth cameras array (DCA) is introduced to create high-fidelity, dense 3D pipeline models. A new camera calibration method is introduced to register the color and the depth information of the cameras into a unified pipe model. By incorporating the calibration outcomes into a robust camera motion estimation approach, dense and complete 3D pipe surface reconstruction is achieved by using only the inline image data collected by a self-powered ILI rover in a single pass through a straight pipeline. The outcomes of the laboratory experiments demonstrate one-millimeter geometrical accuracy and 0.1-pixel photometric accuracy. …
Automatic Delamination Segmentation For Bridge Deck Based On Encoder-Decoder Deep Learning Through Uav-Based Thermography, Chongsheng, Zhexiong Shang, Zhigang Shen
Automatic Delamination Segmentation For Bridge Deck Based On Encoder-Decoder Deep Learning Through Uav-Based Thermography, Chongsheng, Zhexiong Shang, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
Concrete deck delamination often demonstrates strong variations in size, shape, and temperature distribution under the influences of outdoor weather conditions. The strong variations create challenges for pure analytical solutions in infrared image segmentation of delaminated areas. The recently developed supervised deep learning approach demonstrated the potentials in achieving automatic segmentation of RGB images. However, its effectiveness in segmenting thermal images remains under-explored. The main challenge lies in the development of specific models and the generation of a large range of labeled infrared images for training. To address this challenge, a customized deep learning model based on encoder-decoder architecture is proposed …
The Application Of Gray-Scale Level-Set Method In Segmentation Of Concrete Deck Delamination Using Infrared Images, Chongsheng Cheng, Zhigang Shen
The Application Of Gray-Scale Level-Set Method In Segmentation Of Concrete Deck Delamination Using Infrared Images, Chongsheng Cheng, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
Conventional nondestructive delamination detection of concrete pavements through thermography is often based on temperature contrasts between delaminated and sound areas. Non-uniform backgrounds caused by the environmental conditions are often challenging for contrast-based methods to robustly differentiate the delaminated areas from the sound areas. Instead of focusing on the temperature contrast, this study proposes a temperature gradient-based level set method (LSM) to detect boundaries for delamination segmentations. A modified edge indicator function is developed to represent the normalized temperature gradient of a thermal image. The experimental study was conducted to evaluate its applicability and stability for boundary detection in terms of …
A Co-Optimal Coverage Path Planning Method For Aerial Scanning Of Complex Structures, Zhexiong Shang, Justin Bradley, Zhigang Shen
A Co-Optimal Coverage Path Planning Method For Aerial Scanning Of Complex Structures, Zhexiong Shang, Justin Bradley, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
The utilization of unmanned aerial vehicles (UAVs) in survey and inspection of civil infrastructure has been growing rapidly. However, computationally efficient solvers that find optimal flight paths while ensuring high-quality data acquisition of the complete 3D structure remains a difficult problem. Existing solvers typically prioritize efficient flight paths, or coverage, or reducing computational complexity of the algorithm – but these objectives are not co-optimized holistically. In this work we introduce a co-optimal coverage path planning (CCPP) method that simultaneously co-optimizes the UAV path, the quality of the captured images, and reducing computational complexity of the solver all while adhering to …
Bridge Deck Delamination Segmentation Based On Aerial Thermography Through Regularized Grayscale Morphological Reconstruction And Gradient Statistics, Chongsheng Cheng, Zhexiong Shang, Zhigang Shen
Bridge Deck Delamination Segmentation Based On Aerial Thermography Through Regularized Grayscale Morphological Reconstruction And Gradient Statistics, Chongsheng Cheng, Zhexiong Shang, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
Environmental and surface texture-induced temperature variation across the bridge deck is a major source of errors in delamination detection through thermography. This type of external noise poises a significant challenge for conventional quantitative methods such as global thresholding and k-means clustering. An iterative top-down approach is proposed for delamination segmentation based on grayscale morphological reconstruction. A weight-decay function was used to regularize the reconstruction for regional maxima extraction. The mean and coefficient of variation of temperature gradient estimated from delamination boundaries were used for discrimination. The proposed approach was tested on a lab experiment and an in-service bridge deck. The …
Thermographic Laplacian-Pyramid Filtering To Enhance Delamination Detection In Concrete Structure, Chongsheng Cheng, Ri Na, Zhigang Shen
Thermographic Laplacian-Pyramid Filtering To Enhance Delamination Detection In Concrete Structure, Chongsheng Cheng, Ri Na, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
Despite decades of efforts using thermography to detect delamination in concrete decks, challenges still exist in removing environmental noise from thermal images. The performance of conventional temperature-contrast approaches can be significantly limited by environment-induced non-uniform temperature distribution across imaging spaces. Time-series based methodologies were found robust to spatial temperature non-uniformity but requires extended period to collect data. A new empirical image filtering method is introduced in this paper to enhance the delamination detection using blob detection method that originated from computer vison. The proposed method employs a Laplacian of Gaussian filter to achieve multi-scale detection of abnormal thermal patterns by …
Multi-Point Vibration Measurement And Mode Magnification Of Civil Structures Using Video-Based Motion Processing, Zhexiong Shang, Zhigang Shen
Multi-Point Vibration Measurement And Mode Magnification Of Civil Structures Using Video-Based Motion Processing, Zhexiong Shang, Zhigang Shen
Department of Construction Engineering and Management: Faculty Publications
Image-based vibration measurement has gained increased attentions in civil and construction communities. A recent video-based motion magnification method was developed to measure and visualize small structure motions. This new approach presents a potential for low-cost vibration measurement and mode shape identification. Pilot studies using this approach on simple rigid body structures were reported. Its validity on complex outdoor structures has not been investigated. In this study, a non-contact video-based approach for multi-point vibration measurement and mode magnification is introduced. The proposed approach can output a full-field vibration map that increases the efficiency of the current structural health monitoring (SHM) practice. …