Polytechnic University of Valencia Congress, ARQUEOLÓGICA 2.0 - 9th International Congress & 3rd GEORES - GEOmatics and pREServation

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PARAMETRIC GENERATION IN HBIM WORKFLOWS FOR SLAM-BASED DATA: DISCUSSING EXPECTATIONS ON SUITABILITY AND ACCURACY
Giulia Sammartano, Mattia Previtali, Fabrizio Banfi

Last modified: 26-04-2021

Abstract


In the wide framework of Scan-to-BIM 3D modelling procedures, the complexity of the architectural heritage and its components is evidencing a gap of best practices and specification in the HBIM-modeling and thus it is requiring important considerations about the modelling strategies and protocols between the requested level of detail (LOD), the expect accuracy and above all the actual use-oriented requirements. Several works are largely focusing on developing workflows for traditional static LiDAR scanning sensors. However, the chance to benefit from on-site faster data acquisition is needful at times, and procedures are directing toward rapid mapping 3D approaches, evolving from traditional static scanning toward MMS (Mobile Mapping Systems) based on SLAM technology (Simultaneous Localization and Mapping) algorithms implemented in portable devices. The potential of these solutions can contribute to increase a massive cost-effective documentation, and also in view of BIM-HBIM modelling generation, and this needs further researches. At the same time, the descriptive capabilities of this class of portable scanners do not reach the precision of the static solutions. Many time-cost balance evaluations towards an analysis of geometry, grade of generation (GOG) and details can be thus conducted. This paper presents a first comparison between TLS (Faro Focus 3D) and hand-held scanner Zeb Revo (by GeoSLAM) of the entire workflow (from raw data acquisition up to parametric modeling) focusing on the Bramante’s Canonica Court in the Basilica di Sant’Ambrogio. First, the two raw data are compared, considering geometric features (data density, precision, possibility to detect edges, details and accurate curvature). Then, some well-established modelling procedures developed for TLS data, as triangulation mesh and NURBS generation, are applied to MMS point cloud to identify their suitability. Different elements belonging to the architectural structure hierarchy are considered in a multi-scale perspective: the vaulted system of the porch, the columns and the arches of the porch with their different architectural elements.


Keywords


SLAM, MMS, Grade of accuracy, Grade of Generation, HBIM, TLS, Model accuracy, Model scales

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