Parametric Generation in Hbim Workflows for Slam-Based Data: Discussing Expectations on Suitability and Accuracy

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.

From an Integrated Survey With MMS to a Scan-to-Bim Process for Educational Purposes

“…However, it has been validated in an outdoor environment. Sammartano et al (2021) focused on H-BIM (Historic) modeling procedures based on SLAM (Simultaneous Localization and Mapping) technologies, analyzing the geometries and investigating the GOG (grade of generation) from the point of view of time-cost balance. In all the just-mentioned cases, the surveying activities have been planned in advance, and the acquisition phases have been carried out in the best possible way; however, in this case, the learning-by-doing approach took precedence over the compliance and best execution of the data acquisitions, thus the results have to be considered from an educational perspective.…”

“…Through these point clouds, confirmed by the analysis of the deviations, it was possible to achieve results compatible with a representation scale of 1:200 and, only sometimes up to 1:100, in any case with the support of point clouds from UAVs and TLS. During this experience, we have not achieved the accuracies of (Sammartano et al, 2021), and we are aware that a best-planned acquisition path would have helped the final MMS point clouds, though it has to be considered that all the data acquisitions were performed with the students, to implement a learning-by-doing approach, thus obtaining the best result was not the main purpose of the activity.…”

Remote Sensing and City Information Modeling for Revealing the Complexity of Historical Centers

“…These new devices are constantly evolving technologies that need to be assessed against more consolidated techniques such as photogrammetry and TLS. In literature we find different approaches to evaluate iMMS data both in indoor and in outdoor contexts (Nocerino et al, 2017;Chiabrando et al, 2018;Sammartano et al, 2021;Salgues et al, 2020). As regards spherical photogrammetry, in their studies Abate et al (2017) and Barazzetti et al (2018) demonstrate that accurate metric reconstructions can be achieved using low-cost sensors.…”

“…The accuracy evaluation dealt with the geometric features of the point clouds produced and their ability to describe reality. In particular, we followed the approach proposed by Sammartano et al (2021) and Tucci et al (2018). We conducted an analysis of the global accuracy of SFM and SLAM point clouds compared to TLS cloud.…”

Assessing the Quality of the Leica BLK2GO Mobile Laser Scanner versus the Focus 3D S120 Static Terrestrial Laser Scanner for a Preliminary Study of Garden Digital Surveying

“…When evaluating the accuracy of TLS, SfM, and SLAM sensors, usually the TLS is used as the reference scan and the other two are compared against it. Research has already demonstrated that point clouds generated by SfM have lower accuracy than those created by SLAM sensors [7,10,13], but some issues arise when these sensors are used outdoors. Dynamic environments make simultaneous localization and mapping harder and consequently increase the chance of errors [10,14,15].…”