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Three-dimensional CityGML building models in mobile augmented reality: a smartphone-based pose tracking system

International Journal of Digital Earth 2021年第1期14卷 32-51页

作者： Christoph Blut Jörg Blankenbach Geodetic Institute Department of Computing in Civil Engineering and Geo-Information SystemsRWTH Aachen UniversityAachenGermany

Many augmented reality(AR)systems are developed for entertainment,but AR and particularly mobile AR potentially have more application possibilities in other *** example,in civil engineering or city planning,AR could be used in combination with CityGML building models to enhance some typical workflows in planning,execution and operation processes.A concrete example is the geo-referenced on-site visualization of planned buildings or building parts,to simplify planning processes and optimize the communication between the participating *** of the main challenges for the visualization lies in the pose tracking,*** real-time estimation of the translation and rotation of the mobile device to align the virtual objects with *** this paper,we introduce a proof-of-concept fine-grained mobile AR CityGML-based pose tracking system aimed at the mentioned *** system estimates poses by combining 3D CityGML data with information derived from 2D camera images and an inertial measurement unit and is fully self-sufficient and operates without external *** results of our evaluation show that CityGML and low-cost off-the-shelf mobile devices,such as smartphones,already provide performant and accurate mobile pose tracking for AR in civil engineering and city planning.

关键词： Mobile augmented reality pose tracking CityGML 3D city model Android smartphone

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Precise near-ultrasonic tilt determination for smartphones

Precise near-ultrasonic tilt determination for smartphones

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International Conference on Indoor Positioning and Indoor Navigation (IPIN)

作者： Jan Grottke Daniel Grottke Jörg Blankenbach Geodetic Institute and Chair for Computing in Civil Engineering & Geo Information Systems RWTH Aachen University Aachen Germany

ISBN: (数字)9798350366402

ISBN: (纸本)9798350366419

Modern smartphones incorporate numerous sensors that enable relative positioning utilizing the measurement data from the internal inertial measurement unit. Their motion can thus be derived from the magnetometer, gyroscope, and acceleration sensor data. The problem, however, is that the acceleration signals cannot be separated into vertical and horizontal directions during the movement. Therefore, the absolute tilt of the smartphone is often unknown. Nevertheless, this separation is required for many step-based distance determination methods to estimate the length of the detected steps and the acceleration signals measured between the step events for each directional component. Therefore, a near-ultrasound-based distance determination was realized, which applies the Frequency-Modulated Continuous-Wave Radar method (FMCW Radar) to determine the difference between the onboard microphone’s position of the smartphone and the ground (or the nearest reflective surface). These distances allow for a precise inclination determination of the smartphone relative to the ground. The tilt estimation was compared with a camera-based reference position determination. The smartphone’s angle relative to the ground could be determined with a median accuracy of 2.73°, mean accuracy of 3.37°, and 4.56° for the third quartile error.

关键词： Accuracy Magnetic sensors Buildings Estimation Radar Smart phones Floors Video recording Standards Microphones

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TwinGen: Advanced technologies to automatically generate digital twins for operation and maintenance of existing bridges 14th

TwinGen: Advanced technologies to automatically generate dig...

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14th European Conference on Product and Process Modelling, ECPPM 2022

作者： Vilgertshofer, S. Mafipour, M.S. Borrmann, A. Martens, J. Blut, T. Becker, R. Blankenbach, J. Göbels, A. Beetz, J. Celik, F. Faltin, B. König, M. Computational Modeling and Simulation Technical University of Munich Germany Geodetic Institute and Chair for Computing in Civil Engineering & Geo Information Systems RWTH Aachen University Germany Design Computation RWTH Aachen University Germany Computing in Engineering Ruhr University Bochum Germany

ISBN: (纸本)9781032406732

The high effort of operating and maintaining existing infrastructure facilities resulted in a large stock of structurally deficient bridges in most industrialized countries. Today, the condition assessment of bridges is conducted mostly manually. To relieve effort and costs, the digitization and automation of conventional manual, labour-intensive methods is necessary. We interpret the ambiguously used term "digital twin" (DT) in this study as a semantic-geometric model of an existing asset (here, a bridge) that contains all information required for assessing its current condition. This paper proposes an approach to automatically generate the DT of existing bridges from point cloud data (PCD) and images captured from the structure. The PCD of the bridge is semantically segmented by means of ML techniques, and a digital model is created using parametric modeling. Subsequently, detected damages and data from existing bridge maintenance systems are linked to the model to create a full DT. This paper reports the main results of the TwinGen research project: The digital twinning process of bridges can be automated to a large extent, in order to efficiently support the maintenance process of bridges. © 2023 the Author(s).

关键词： Bridges

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Thermal Reality Capturing with the Microsoft Hololens 2 for Energy System Analysis

SSRN

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SSRN 2023年

作者： Kinnen, Tristan Blut, Christoph Effkemann, Christoph Blankenbach, Jörg Geodetic Institute and Chair for Computing in Civil Engineering & Geo Information Systems RWTH Aachen University Germany

Using digital methods to analyze the often highly complex structures of technical building equipment (TBE) holds great potential for identifying energy savings. For digitizing TBE, we evaluated the Microsoft HoloLens 2 (MHL2), since it promises to be a mobile and cost-effective solution and found that the MHL2 can be a suitable instrument for as-built acquisition, depending on the use-case’s accuracy requirements. The depth sensor of the MHL2 operates in a low single-digit centimeter accuracy range, while the position tracking inaccuracy is more significant. Furthermore, we extended the acquisition system with an external thermal camera to generate both, RGB and thermal point clouds. Additionally, we built a custom 3D calibration setup that allows us to calibrate both cameras in parallel and achieve promising accuracies for the level of detail of the resulting RGB and thermal point clouds and thus for the energy system analysis approach. © 2023, The Authors. All rights reserved.

关键词： Cameras

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VI-SLAM2tag: Low-Effort Labeled Dataset Collection for Fingerprinting-Based Indoor Localization

arXiv

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arXiv 2022年

作者： Laska, Marius Schulz, Till Grottke, Jan Blut, Christoph Blankenbach, Jörg Geodetic Institute and Chair for Computing in Civil Engineering & Geo Information Systems RWTH Aachen University Aachen Germany

Fingerprinting-based approaches are particularly suitable for deploying indoor positioning systems for pedestrians with minimal infrastructure costs. The accuracy of the method, however, strongly depends on the quality of collected labeled fingerprints within the calibration phase, which is a tedious process when done manually in a static fashion. We present VI-SLAM2tag, a system for auto-labeling of dynamically collected fingerprints using the visual-inertial simultaneous localization and mapping (VI-SLAM) module of ARCore. ARCore occasionally updates its internal coordinate system. Mapping the entire trajectory to a target coordinate system via a single transformation thus results in large drift effects. To solve this, we propose a strategy for determining locally optimal sub-trajectory transformations. Our system is evaluated with respect to the accuracy of the generated position labels using a geodetic tracking system. We achieve an average labeling error of roughly 50 cm for trajectories of up to 15 minutes, which is sufficient for fingerprinting-based localization. We demonstrate this by collecting a multi-floor dataset including WLAN and IMU data and show how it can be used to train neural network based models that achieve a positioning accuracy of roughly 2 m. VI-SLAM2tag and the dataset are made publicly available. © 2022, CC BY.

关键词： Trajectories

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Topology Preserving Input Image for Convolutional Neural Network Based Indoor Localization

Topology Preserving Input Image for Convolutional Neural Net...

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International Conference on Indoor Positioning and Indoor Navigation (IPIN)

作者： Marius Laska Jörg Blankenbach Geodetic Institute and Chair for Computing in Civil Engineering & Geo Information Systems RWTH Aachen University Aachen Germany

Convolutional neural networks (CNNs) have made a significant impact on problems such as image classification. By learning feature maps via convolutional layers, local features of the images are extracted. Recently, CNNs have also been applied for fingerprinting based indoor localization that use the received signal strength (RSS) of WLAN access points (APs) to construct the fingerprints. The input images are created from the RSS vector by arbitrarily assigning APs to pixel positions of the 2D-image. Local information is lost by this procedure, which contradicts the prior learned by CNN that close pixels are more related than distant ones. In this work we try to preserve the topology of the APs within the constructed 2D-input image. We propose an unsupervised method to estimate pairwise relative AP distances from unlabeled fingerprints. We develop an algorithm to generate an AP-image mapping that assures highly related APs will appear close in the resulting image. On the public fingerprinting benchmark dataset from UJI, we empirically show that the topology preserving AP-images (TPAI) significantly benefit classification accuracy of various recently proposed CNN architectures.

关键词： Location awareness Wireless LAN Network topology Indoor navigation Neural networks Fingerprint recognition Feature extraction

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Indoor localization for pedestrians with real-time capability using multi-sensor smartphones

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geo-Spatial information Science 2019年第2期22卷 73-88,I0001页

作者： Catia Real Ehrlich Jörg Blankenbach Geodetic Institute and Chair for Computing in Civil Engineering&Geo Information Systems RWTH Aachen UniversityAachenGermany

The localization of persons or objects usually refers to a position determined in a spatial reference ***,this is usually accomplished with Global Navigation Satellite systems(GNSS).However,the automatic positioning of people in GNSS-free environments,especially inside of buildings(indoors)poses a huge ***,satellite signals are attenuated,shielded or reflected by building components(*** or ceilings).For selected applications,the automatic indoor positioning is possible based on different technologies(***,RFID,or UWB).However,a standard solution is still not *** indoor positioning systems are only suitable for specific applications or are deployed under certain conditions,*** infrastructures or sensor ***,as popular cost-effective multi-sensor systems,is a promising indoor localization platform for the mass-market and is increasingly coming into ***’s devices are equipped with a variety of sensors that can be used for indoor *** this contribution,an approach to smartphone-based pedestrian indoor localization is *** novelty of this approach refers to a holistic,real-time pedestrian localization inside of buildings based on multisensor smartphones and easy-to-install local positioning *** this purpose,the barometric altitude is estimated in order to derive the floor on which the user is *** 2D position is determined subsequently using the principle of pedestrian dead reckoning based on user's movements extracted from the smartphone *** order to minimize the strong error accumulation in the localization caused by various sensor errors,additional information is integrated into the position *** building model is used to identify permissible(***,passageways)and impermissible(***)building areas for the *** technologies contributing to higher precision and robustness are also *** the fusion of diffe

关键词： Indoor positioning MEMS recursive Bayesian estimation particle filter sensor fusion Bluetooth beacons WLAN fingerprinting magnetic anomalies

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CityGML goes mobile: application of large 3D CityGML models on smartphones

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International Journal of Digital Earth 2019年第1期12卷 25-42页

作者： Christoph Blut Timothy Blut Jörg Blankenbach Department of Computing in Civil Engineering and Geo Information Systems Geodetic InstituteRWTH Aachen UniversityAachenGermany

CityGML,a semantic information model for digital/virtual city models has become quite popular in various *** the data format is still actively under development,it is already supported by different software solutions,especially GIS-based desktop *** systems on the other hand are still neglected,even though the georeferenced objects of CityGML have many application fields,for example,in the currently popular area of location-based Augmented *** this paper we present an independent multi-platform CityGML viewer,its architecture and specific implementation techniques that we use to realize and optimize the process of visualizing CityGML data for use in Augmented *** main focus lies in improving the implementation on mobile devices,such as smartphones,and assessing its usability and performance in comparison to web-based *** to the constrained hardware resources of smartphones,it is a particular challenge to handle complex 3D objects and large virtual worlds as provided by CityGML,not only in terms of memory and storage space,but also with respect to mobile processing units and display sizes.

关键词： CityGML city model android 3D visualization real-time rendering

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GIM and BIM

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PFG – Journal of Photogrammetry, Remote Sensing and geoinformation Science 2020年第1期88卷 33-42页

作者： Herle, Stefan Becker, Ralf Wollenberg, Raymond Blankenbach, Jörg Geodetic Institute and Chair for Computing in Civil Engineering & Geo Information Systems RWTH Aachen University Aachen Germany

geospatial information modelling (GIM) is used for decades to document phenomena of the real world. Visualizing and analysing GIM data are usually accomplished by geographic information system tools. The construction industry, on the other hand, uses usually computer-aided design (CAD) tools to plan buildings. With the introduction of building information modelling (BIM), modelling in CAD was enhanced to the entire life cycle of constructions. BIM and GIM are not independent of each other, e.g. BIM uses geospatial data for planning purposes. However, integrating both is challenging since the modelling methods differ. The paper describes approaches to establish interoperability between models of both domains. A literature review reveals the problems and challenges different researchers tackled to achieve interoperability.

关键词：

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Enabling BIM for property management of existing buildings based on automated As-IS capturing 36

Enabling BIM for property management of existing buildings b...

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36th International Symposium on Automation and Robotics in Construction, ISARC 2019

作者： Becker, R. Lublasser, E. Martens, J. Wollenberg, R. Zhang, H. Brell-Cokcan, S. Blankenbach, J. Geodetic Institute Chair for Computing in Civil Engineering and Geo Information Systems RWTH Aachen University Germany Individualized Production in Architecture RWTH Aachen University Germany

Digitization and automation in construction are increasing particularly due to the establishment of Building information Modelling (BIM). The models of BIM contain geometric as well as semantic information. The level of abstraction ranges from coarse models up to detailed modeled technical components of the buildings. So far, BIM has been developed and used for the planning and construction phase of the building’s lifecycle. In order to fully use the benefits of BIM also for the operation and refurbishment phase, BIM models need to provide a reliable data basis of the as-built and respectively the as-is situation. However, up to now many properties have neither been planned nor constructed using BIM, at times not even digital planning information is available. Therefore, the digital model must be created from the real world. The author’s research proposes the development of an automated as-is capturing process of existing buildings as well as the data integration into BIM as a basis for property management. Suitable capturing techniques have been analyzed. Up to now, these techniques and the subsequent data transfer are still characterized by lots of manual work. Accelerating this process requires methods for the automation of data segmentation, classification and the modeling process. Conventional data capturing techniques such as laser scanning measure only visible surfaces. However, knowledge about inbuilt materials, constructional layers or thickness of e.g. walls is also important for optimized planning and utilization. This paper summarizes the results of a joint research project in cooperation with a property management company. © 2019 International Association for Automation and Robotics in Construction I.A.A.R.C. All rights reserved.

关键词： Robotics

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