Search

Reliable traffic infrastructure is a key factor for any country's economy. However, aging bridges often require renovation or reconstruction. Promising approaches for enhancing asset management and cost reduction are digital twins and predictive maintenance strategies. However, the creation of geometric-semantic as-is models as a basis for digital twins currently involves labor-intensive manual data capture and modeling. Modern deep learning models, such as Kernel Point Convolution (KPConv) show promising results in reducing the time needed to create digital twins by semantically segmenting point cloud data but have so far been hindered by the lack of a reliable quality measure, which can predict when the model's prediction can be trusted. This is especially viable in the construction industry, where objects and sensors may vary widely between projects and contractors. In this work, we present Bayesian neural networks, implemented through Variational Inference and Monte-Carlo dropout as approaches to conducting inference with KPConv, which show improvements in the confidence estimation and out-of-domain (OOD) detection in the scans of typical infrastructure point clouds. When confronted with different domain shifts to the test data, such as a change of scanning device and introduction of unseen classes the proposed model showed a 25.3% decrease in expected calibration error (ECE) and a 4.82 increase in OOD detection in terms of outlier-intersection-over-union (O-IoU) on average with respect to a deterministic baseline. • Bayesian neural networks applied in point cloud semantic segmentation. • Training stochastic models with Variational Inference improve calibration. • Out of domain detection was improved with a single stochastic layer. • Model robustness to domain shift from mobile to terrestrial laser scanner. [ABSTRACT FROM AUTHOR]

Large volumes of 3D parametric datasets, such as building information modeling (BIM), are the foundation for developing and applying smart city and digital twin technologies. Those datasets are also considered valuable tools for efficiently managing rebuilt structures during the operation and maintenance stages. Nevertheless, current approaches developed for the scan-to-BIM process rely on manual or semi-automatic procedures and insufficiently leverage semantic data in point clouds. These methods struggle to accurately represent large-scale indoor complex layouts and extract details from irregular-shaped unstructured elements, causing inefficiencies in BIM model generation. To address these issues, we propose an innovative scan-to-BIM framework based on deep learning algorithms and raw point cloud data, enabling the automatic generation of 3D models for both structured and unstructured indoor elements. Initially, we propose an enhanced deep learning neural network to improve the point clouds' semantic segmentation accuracy. Subsequently, an efficient workflow is developed to reconstruct 3D building models of structured indoor scenes. The proposed workflow can reconstruct large-scale data with multiple room layouts of Manhattan or non-Manhattan structures and reconstruct 3D models automatically by using a BIM parametric algorithm implemented in Revit software. Moreover, we introduce a robust method for unstructured elements to automatically generate corresponding 3D BIM models, even when the incorporating semantic information is incomplete. The proposed approach was evaluated on synthetic and real data for different scales and complexities of indoor scenes. The results of the experiments demonstrate that the improved model significantly enhances the overall semantic segmentation accuracy compared to the baseline models. The proposed scan-to-BIM framework is efficient for indoor element 3D reconstruction, achieving precision, recall, and F-score values ranging from 96% to 99%. The generated BIM models are competitive with traditional methods regarding model completeness and geometric accuracy. • We propose an innovative scan-to-BIM framework based on deep learning algorithms: • We propose an enhanced deep-learning neural network to improve the point clouds' semantic segmentation accuracy. • A novel and efficient workflow is developed to reconstruct 3D building models of structured indoor scenes. It can reconstruct large-scale data with multiple room layouts in 3D model automatically by using a BIM parametric • For unstructured elements, we propose a robust method to automatically generate 3D BIM models, even when the semantic information is incomplete. [ABSTRACT FROM AUTHOR]

Accurate and efficient inspection of rebar dimensions has proven to be a persistent challenge for researchers and practitioners. This paper introduces a semantically enriched 3D model-based system that employs computer vision and deep learning for location-aware identification and tracking of rebar issues. The system comprises four modules: (A) digital twin generation, (B) segmentation, (C) inspection, and (D) issue identification and tracking. The generation module constructs 3D models from rebar structures. The segmentation and inspection modules analyze the 3D models, enriching them with semantic information. The issue identification and tracking module exchanges information between the semantically enriched 3D models and the building information models across time. An experiment on a column rebar cage is conducted. A precision of over 90% and a recall of over 97% are reported in 3D instance segmentation. Diameter inspection achieves an accuracy of 95.5% for large-size rebars. Spacing inspection achieves a mean relative error of 0.98%. The defective spacing is identified and tracked. • Fuses deep learning and computer vision to construct 3D semantic rebar model. • BIM- and digital-twin-based information system fulfills rebar quality control. • Autonomous rebar inspection pipeline directly generates issue reports from images. [ABSTRACT FROM AUTHOR]

This paper establishes a digital twin (DT) enabled model that aims to achieve real-time monitoring and control to enhance the overall performance of tunnel boring machines (TBM) during excavation. Through the Internet of Things (IoT) sensors that are installed on TBM, the actual operating status is transferred from the physical object to the digital model. Deep learning models that integrated graph convolutional network (GCN) and long short-term memory (LSTM) networks are employed for reliable TBM performance estimation. An online multi-objective optimization (MOO) approach is then proposed to determine the optimal operating parameters for advanced control. Real data from Singapore's Circle Line 6 C885 project is utilized as a case study to examine the applicability of the developed digital twin model. TBM's penetration rate, over-excavation ratio, energy consumption, and tool wear are selected as the objectives (O 1 to O 4) for optimization. The results indicate that (1) The digital twin model can provide a reliable estimation of TBM's performance indicators with a high coefficient of determination (R 2) values. (2) TBM's overall performance can be effectively improved through the proposed online optimization method, with an overall improvement of 21.12%. (3) The proposed online optimization method is more practical and creates better improvement than the conventional MOO approach. This study addresses the existing research gaps of lacking a reliable method to guide TBM operation with enhanced performances for the major objectives. It also contributes to proposing a novel intelligent approach that integrates DT, deep learning, and an online-NSGA-II method for TBM operation optimization during tunnel excavation. • A digital twin enabled approach is proposed for real-time intelligent control for TBM operation. • An MOO approach that integrates deep-learning and online optimization is established. • Data from a realistic tunnel project in Singapore is used to demonstrate as a case study. • TBM's efficiency, safety, energy consumption and tool wear are considered as objectives. • An overall improvement of 21.12% is achieved by implementing the proposed method. [ABSTRACT FROM AUTHOR]