Including widespread geometry formats in semantic graphs using RDF literals

The exchange of building data involves both geometric and non-geometric data. A promising Linked Data approach is to embed data from existing geometry formats inside Resource Description Framework (RDF) literals. Based on a study of relevant specifications and related work, this toolset-independent approach was found suitable for the exchange of geometric construction data. To implement the approach in practice, the File Ontology for Geometry formats (FOG) and accompanying modelling method is developed. In a proof-of-concept web application that uses FOG, is demonstrated how geometry descriptions of different existing formats are automatically recognised and parsed

Laser scanning, monitoring and analysis of a reconstructed masonry vault

Reconstruction of historic building elements is often necessary in adaptive re-use projects. Optimally this is performed with as much original material as can be sal- vaged. However, the use of hydraulic lime mortars in reconstructed masonry can lead to long curing time and excessive deformation under mechanical loadsThe authors would like to thank V. Wirix from Denys NV and F. Noë from VK Engineering for their support of the on-site work, and WTA-NL-VL for the financial supportPostprint (published version

Investigation of coronal leakage of root fillings after smear layer removal with EDTA or Nd:YAG lasing through capillary flow porometry

Objective: This study investigates the effects of Nd:YAG laser irradiation combined with different irrigation protocols on the marginal seal of root fillings. Background data: Limited information exists regarding the effects of morphologic changes to root canal (RC) walls after Nd:YAG laser irradiation after smear-layer removal with EDTA on the sealing ability of root fillings. Methods: The 75 root-filled teeth (5 × 15 teeth) were analyzed for through-and-through leakage by using capillary flow porometry (CFP). The RC cleaning procedure determined the assignment to a group: (1) irrigation with NaOCl 2.5% and EDTA 17% or standard protocol (SP), (2) SP + Nd:YAG lasing (dried RC), (3) NaOCl 2.5% + Nd:YAG lasing (dried RC), (4) SP + Nd:YAG lasing (wet RC), or (5) NaOCl 2.5% + Nd:YAG lasing (wet RC). Groups 1r to 5r consisted of the same filled teeth with resected apices up to the most apical point of the preparation length. Resection was performed after the first CFP measurement. Roots were filled with cold lateral condensation. CFP was used to assess minimum, mean flow and maximum pore diameters after 48 h, and immediately after these measurements, including root resection. Statistics were performed by using nonparametric tests (p > 0.05). An additional three roots per group were submitted to SEM of the RC wall. Results: Through-and-through leakage was observed in all groups. Statistically significant differences were observed in maximum pore diameter: 1r > 3r, and 1r > 5r; in mean flow pore diameter: 1r > 2r, 2r < 4r (p < 0.05). Typical Nd:YAG glazing effects were observed when the smear layer was present and exposed to the laser fiber (i.e., in the groups without use of EDTA) or when the fiber tip made direct contact with a smear-layer free RC wall. Conclusions: The reduction in through-and-through leakage is significantly higher with the Nd:YAG laser as smear-layer modifier than when smear layer is removed with an EDTA rinsing solution

Numerical analysis of settlement-induced damage to a masonry church nave wall

Differential soil settlements can induce structural damage to heritage buildings, causing not only economic but also cultural value losses. In 1963, the Saint Jacob’s church in Leuven was permanently closed to the public because of severe settlement-induced damage caused by insufficient bearing capacity of the founda- tion. Currently, the church is stabilized using a temporary shoring system. This work aims at implementing a practical modelling approach to predict damage on church nave walls subjected to differential settlements. For that purpose, a finite element model of the Saint Jacob’s church nave was generated and validated through on- site monitoring data including levelling, damage survey and laser scanningThis work was done within the framework of the GEPATAR project (“GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium” BR/132/A6/Gepatar), supported by BRAIN.be, Belspo.Postprint (published version

Scan-to-BIM output validation : towards a standardized geometric quality assessment of building information models based on point clouds

The use of Building Information Modeling (BIM) for existing buildings based on point clouds is increasing. Standardized geometric quality assessment of the BIMs is needed to make them more reliable and thus reusable for future users. First, available literature on the subject is studied. Next, an initial proposal for a standardized geometric quality assessment is presented. Finally, this method is tested and evaluated with a case study. The number of specifications on BIM relating to existing buildings is limited. The Levels of Accuracy (LOA) specification of the USIBD provides definitions and suggestions regarding geometric model accuracy, but lacks a standardized assessment method. A deviation analysis is found to be dependent on (1) the used mathematical model, (2) the density of the point clouds and (3) the order of comparison. Results of the analysis can be graphical and numerical. An analysis on macro (building) and micro (BIM object) scale is necessary. On macro scale, the complete model is compared to the original point cloud and vice versa to get an overview of the general model quality. The graphical results show occluded zones and non-modeled objects respectively. Colored point clouds are produced and integrated in the BIM. On micro scale, the relevant surface parts are extracted per BIM object and compared to the complete point cloud. Occluded zones are extracted based on a maximum deviation. What remains is classified according to the LOA specification. The numerical results are integrated in the BIM with the use of object parameters

Clustering of Wall Geometry from Unstructured Point Clouds Using Conditional Random Fields

status: publishe

Unsupervised reconstruction of Building Information Modeling wall objects from point cloud data

Scan-to-BIM of existing buildings is in high demand by the construction industry. However, these models are costly and time-consuming to create. The automation of this process is still subject of ongoing research. Current obstacles include the interpretation and reconstruction of raw point cloud data, which is complicated by the complexity of built structures, the vast amount of data to be processed and the variety of objects in the built environment. This research aims to overcome the current obstacles and reconstruct the structure of buildings in an unsupervised manner. More specifically, a novel method is presented to automatically reconstruct BIM wall objects and their topology. Key contributions of the method are the ability to reconstruct different wall axis and connection types and the simultaneous processing of entire multi-story structures. The method is validated with the Stanford 2D–3D-Semantics Dataset (2D–3D-S).status: Published onlin

Topology Reconstruction of BIM Wall Objects from Point Cloud Data

status: publishe