scholarly journals HIGH ACCURATE POINTWISE (GEO-)REFERENCING OF A K-TLS BASED MULTI-SENSOR-SYSTEM

2018 ◽  
Vol IV-4 ◽  
pp. 81-88 ◽  
Author(s):  
J. Hartmann ◽  
P. Trusheim ◽  
H. Alkhatib ◽  
J.-A. Paffenholz ◽  
D. Diener ◽  
...  
Keyword(s):  
Kalman Filter ◽  
Point Cloud ◽  
Laser Scanning ◽  
Laser Scanner ◽  
High Accuracy ◽  
Laser Tracker ◽  
3D Point Cloud ◽  
Filter Model ◽  
Measurement Frequency ◽  
Set Up

<p><strong>Abstract.</strong> In recent years, the requirements in the industrial production, e.g., ships or planes, have been increased. In addition to high accuracy requirements with a standard deviation of 1<span class="thinspace"></span>mm, an efficient 3D object capturing is required. In terms of efficiency, kinematic laser scanning (k-TLS) has been proven its worth in recent years. It can be seen as an alternative to the well established static terrestrial laser scanning (s-TLS). However, current k-TLS based multi-sensor-systems (MSS) are not able to fulfil the high accuracy requirements. Thus, a new k-TLS based MSS and suitable processing algorithms have to be developed. In this contribution a new k-TLS based MSS will be presented. The main focus will lie on the (geo-)referencing process. Due to the high accuracy requirements, a novel procedure of external (geo-)referencing is used here. Hereby, a mobile platform, which is equipped with a profile laser scanner, will be tracked by a laser tracker. Due to the fact that the measurement frequency of the laser scanner is significantly higher than the measurement frequency of the laser tracker a direct point wise (geo-)referencing is not possible. To enable this a Kalman filter model is set up and implemented. In the prediction step each point is shifted according to the determined velocity of the platform. Because of the nonlinear motion of the platform an iterative extended Kalman filter (iEKF) is used here. Furthermore, test measurements of a panel with the k-TLS based MSS and with s-TLS were carried out. To compare the results, the 3D distances with the M3C2-algorithm between the s-TLS 3D point cloud and the k-TLS 3D point cloud are estimated. It can be noted, that the usage of a system model for the (geo-)referencing is essential. The results show that the mentioned high accuracy requirements have been achieved.</p>

3D LASER SCANNING FOR PRESERVATION AND STRUCTURAL MONITORING OF HISTORIC CALIFORNIA ADOBE MISSIONS

2016 ◽  
Vol 11 (4) ◽  
pp. 1-14 ◽  
Author(s):  
H. M. Böttger ◽  
C. J. Arce Bazán ◽  
N. P. Saarman
Keyword(s):  
Native Americans ◽  
San Francisco ◽  
Point Cloud ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Monitoring Program ◽  
Lessons Learned ◽  
Structural Monitoring ◽  
Special Focus ◽  
3D Point Cloud

INTRODUCTION At the University of San Francisco Architecture & Community Design Program, the Architectural Engineering curriculum utilizes a Leica ScanStation C10 3D Laser Scanner to document historic structures and monitor their structural behavior. Some of the oldest structures in the State of California are the historic adobe missions built by Native Americans and Spanish Catholic missionaries between 1769 and 1833. California is a region of very high seismic activity, and the adobe structures have withstood significant earthquakes and other erosive or destructive forces over their lifetime. However, they are sensitive structures in need of active preservation and very few original adobe buildings remain. Working together with local structural engineers who specialize in seismic restoration of historic adobe structures, USF students have conducted laser scanning at Mission Santa Cruz and Mission San Miguel Arcángel, creating extensive 3D point cloud records, and developing architectural drawings which establish the current state of these structures for the purposes of historic preservation and structural study. Because of the delicate and irregular nature of these structures, the 3D laser scanner is the most appropriate tool for detailed yet non-invasive documentation. Completed in 1821, Mission San Miguel Arcángel suffered significant damage in the nearby 2003 San Simeon earthquake. The original adobe structure has undergone partial repairs such as banding at the top of the walls of the Sacristy. Using the 3D laser scanner, thorough scans are stitched together to create full interior and exterior 3D point cloud files, which are processed in Leica Cyclone and Autodesk Recap, and then imported into AutoCAD to create detailed line drawings of plans, elevations and sections of significant areas. Wall lean and other indicators of crack progress and deterioration are areas of special focus. With these records, a structural monitoring program has begun to document the condition of the buildings in wet seasons and dry seasons, and to determine the long-term effect of seismic restorations which have been implemented. This paper presents a detailed account of the process, pedagogical value and structural and architectural lessons learned over the course of the 3D scanning of these valuable heritage landmarks.

scholarly journals UAV-BASED ACQUISITION OF 3D POINT CLOUD – A COMPARISON OF A LOW-COST LASER SCANNER AND SFM-TOOLS

2015 ◽  
Vol XL-3/W3 ◽  
pp. 335-341 ◽  
Author(s):  
D. Mader ◽  
R. Blaskow ◽  
P. Westfeld ◽  
H.-G. Maas
Keyword(s):  
Structure From Motion ◽  
Point Cloud ◽  
Laser Scanning ◽  
Near Infrared ◽  
Low Cost ◽  
Laser Scanner ◽  
Infrared Camera ◽  
Image Data ◽  
3D Point Cloud ◽  
Efficient System

The Project ADFEX (Adaptive Federative 3D Exploration of Multi Robot System) pursues the goal to develop a time- and cost-efficient system for exploration and monitoring task of unknown areas or buildings. A fleet of unmanned aerial vehicles equipped with appropriate sensors (laser scanner, RGB camera, near infrared camera, thermal camera) were designed and built. A typical operational scenario may include the exploration of the object or area of investigation by an UAV equipped with a laser scanning range finder to generate a rough point cloud in real time to provide an overview of the object on a ground station as well as an obstacle map. The data about the object enables the path planning for the robot fleet. Subsequently, the object will be captured by a RGB camera mounted on the second flying robot for the generation of a dense and accurate 3D point cloud by using of structure from motion techniques. In addition, the detailed image data serves as basis for a visual damage detection on the investigated building. <br><br> This paper focuses on our experience with use of a low-cost light-weight Hokuyo laser scanner onboard an UAV. The hardware components for laser scanner based 3D point cloud acquisition are discussed, problems are demonstrated and analyzed, and a quantitative analysis of the accuracy potential is shown as well as in comparison with structure from motion-tools presented.

Error Modelling and Optimal Estimation of Laser Scanning Aided Inertial Navigation System in GNSS-Denied Environments

2018 ◽  
Vol 72 (3) ◽  
pp. 741-758 ◽  
Author(s):  
W.I. Liu ◽  
Zhixiong Li ◽  
Zhichao Zhang
Keyword(s):  
Kalman Filter ◽  
Navigation System ◽  
Laser Scanning ◽  
Inertial Navigation System ◽  
Laser Scanner ◽  
Inertial Navigation ◽  
Integration Algorithm ◽  
Biased Estimation ◽  
State Estimations ◽  
Estimation And Filtering

A Laser Scanning aided Inertial Navigation System (LSINS) is able to provide highly accurate position and attitude information by aggregating laser scanning and inertial measurements under the assumption that the rigid transformation between sensors is known. However, a LSINS is inevitably subject to biased estimation and filtering divergence errors due to inconsistent state estimations between the inertial measurement unit and the laser scanner. To bridge this gap, this paper presents a novel integration algorithm for LSINS to reduce the inconsistences between different sensors. In this new integration algorithm, the Radial Basis Function Neural Networks (RBFNN) and Singular Value Decomposition Unscented Kalman Filter (SVDUKF) are used together to avoid inconsistent state estimations. Optimal error estimation in the LSINS integration process is achieved to reduce the biased estimation and filtering divergence errors through the error state and measurement error model built by the proposed method. Experimental tests were conducted to evaluate the navigation performance of the proposed method in Global Navigation Satellite System (GNSS)-denied environments. The navigation results demonstrate that the relationship between the laser scanner coordinates and the inertial sensor coordinates can be established to reduce sensor measurement inconsistencies, and LSINS position accuracy can be improved by 23·6% using the proposed integration method compared with the popular Extended Kalman Filter (EKF) algorithm.

scholarly journals FINE REGISTRATION OF KILO-STATION NETWORKS - A MODERN PROCEDURE FOR TERRESTRIAL LASER SCANNING DATA SETS

2016 ◽  
Vol XLI-B5 ◽  
pp. 485-492
Author(s):  
J.-F. Hullo
Keyword(s):  
Laser Scanning ◽  
Laser Scanner ◽  
Data Sets ◽  
Data Set ◽  
Information Models ◽  
3D Network ◽  
Laser Scanners ◽  
Building Information ◽  
Set Up ◽  
Fine Registration

We propose a complete methodology for the fine registration and referencing of kilo-station networks of terrestrial laser scanner data currently used for many valuable purposes such as 3D as-built reconstruction of Building Information Models (BIM) or industrial asbuilt mock-ups. This comprehensive target-based process aims to achieve the global tolerance below a few centimetres across a 3D network including more than 1,000 laser stations spread over 10 floors. This procedure is particularly valuable for 3D networks of indoor congested environments. In situ, the use of terrestrial laser scanners, the layout of the targets and the set-up of a topographic control network should comply with the expert methods specific to surveyors. Using parametric and reduced Gauss-Helmert models, the network is expressed as a set of functional constraints with a related stochastic model. During the post-processing phase inspired by geodesy methods, a robust cost function is minimised. At the scale of such a data set, the complexity of the 3D network is beyond comprehension. The surveyor, even an expert, must be supported, in his analysis, by digital and visual indicators. In addition to the standard indicators used for the adjustment methods, including Baarda’s reliability, we introduce spectral analysis tools of graph theory for identifying different types of errors or a lack of robustness of the system as well as <i>in fine</i> documenting the quality of the registration.

scholarly journals Documentación 3D para la conservación del patrimonio histórico: el castillo de Priego de Córdoba

2021 ◽  
Vol 12 (24) ◽  
pp. 115
Author(s):  
Diego Francisco García-Molina ◽  
Ramón González-Merino ◽  
Jesús Rodero-Pérez ◽  
Bartolomé Carrasco-Hurtado
Keyword(s):  
Local Governments ◽  
Point Cloud ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Digital Preservation ◽  
3D Models ◽  
City Council ◽  
Heritage Management ◽  
Technological Advances ◽  
The 19Th Century

<p class="VARKeywords">One of the main objectives of heritage management policies is to promote measures aimed at the maintenance, restoration and enhancement of cultural and archaeological assets. To guarantee this, the responsible institutions must promote actions for the dissemination and transference of cultural heritage, as well as promoting actions with the greatest possible rigour, developing scientific and technical studies that support and improve intervention methods. Recent technological advances in fields such as photogrammetry, digital terrestrial scanning and 3D modelling have made a significant contribution to the digital preservation and dissemination of architectural heritage.</p><p class="VARKeywords">European administrations, in their desire of regional development, as well as the central or local governments have notably boosted the recovery of their rich and diverse heritage. A particular case is Priego de Cordoba’s Castle, a stronghold which was one of the most important monumental icons of the Andalusian period.</p><p class="VARKeywords">Currently, this site is the main target of many architectural interventions and a model due to the implementation of last generation techniques in digital preservation. The local archaeological department promotes a large number of interventions and archaeological excavations. This has made a priority to get a qualitative geometrical 3D documentation, and therefore a constantly updated the point cloud (xyzRGB).</p><p class="VARKeywords">This paper is focussed on presenting the results of the digital preservation process through 2D planimetry obtained from photogrammetric technics, 3D models, and geospatial data. These techniques are a previous step to large architectonical intervention planned in Priego de Cordoba’s Castle, in particular, the identified structures as Wall 1 and Tower 1.</p><p class="VARKeywords">Two out of the three studied structures can be found in Wall 1. They correspond to a cobblestone pavement located in the rampart of the Wall 1, which is a post-medieval period; a double-stepped semi-underground path, excavated in the infill of the wall. The third structure studied in this paper consists of a well, which drills vertically the infill of the wall of the Tower 1. This feature is interpreted in the last research as a vertical well to place the weights of the clock sited in this tower until the 19th century.</p><p class="VARKeywords">This work combines two techniques of geometric documentation to obtain a more complete point cloud. The terrestrial laser scanning, and the photogrammetry due to the higher colour performance, along with the completion of the point cloud obtained with the laser scanner. Along with this study, we will analyse the features which will better define the best technique to fit the documentation of the different structures. Their geometric characteristics, the incidence of sunlight or the accessibility will condition the use and choice of the technique.</p><p class="VARKeywords">We have stated that there is software nowadays which makes it easier to access and consult the information through new computing hardware. Besides, we have highlighted the importance of knowledge and synergy from the different stakeholders implied (city council, technological centre and private companies). The final goal consists of making the society aware of the capital importance of digital preservation as well as dissemination of science.</p>

scholarly journals Point-Cloud Models of Historical Barns – Spatial Discrepancies of Laser Scanning versus Robotic Total Station

10.29007/2493 ◽  
2020 ◽  
Author(s):  
Gustavo Maldonado ◽  
Marcel Maghiar ◽  
Brent Tharp ◽  
Dhruv Patel
Keyword(s):  
Service Learning ◽  
Point Cloud ◽  
Laser Scanning ◽  
3D Point Cloud ◽  
Spatial Accuracy ◽  
Total Station ◽  
Cloud Models ◽  
Bulloch County ◽  
Southern University ◽  
Robotic Total Station

This study considers the generation of virtual, 3D point-cloud models of seven deteriorating historical, agricultural barns in Bulloch County, Georgia, USA, for preservation purposes. The work was completed as a service-learning project in a course on Terrestrial Light Detection and Ranging (T-LiDAR), offered at Georgia Southern University. The resulting models and fly-through videos were donated to Bulloch County Historical Society and to the Georgia Southern Museum, to make them available to the general public and future generations. Additionally, one of the seven barns was selected to be extensively measured to estimate the relative spatial accuracy of all seven resulting 3D point-cloud models, with respect to measurements completed with a highly accurate instrument. Three accurate benchmarks were established around it for georeferencing purposes. The positions of 44 points were measured in the field via an accurate, one- second, robotic total-station (RTS) instrument. Also, the coordinates of the same points were acquired from within georeferenced and non-georeferenced point-cloud models. These points defined 259 distances. They were compared to determine their discrepancy statistics. It was observed that this process produced virtual models with an approximate maximum spatial discrepancy of one-half inch (0.5 in) with respect to measurements performed by a highly accurate RTS device. There were no substantial differences in the relative accuracies of the georeferenced and non-georeferenced models.

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