CitA BIM Gathering, September 20th 2023
A critical analysis of speed and accuracy when updating structural asbuilt BIMs with visual programming and point-cloud survey data Rubens Lage Lopes1 and Davitt Lamon2 School of Surveying and Construction Innovation Technological University Dublin, Dublin, Ireland E-mail: 1rubenslage@gmail.com
2
davitt.lamon@tudublin.ie
Abstract ̶ In the continuously evolving field of construction, consistent updating of as-built Building Information Models (BIMs) is crucial. However, the existing methods often lead to fragmented information flow, risking the loss of important design data during the transition. This research presents a novel approach aimed at enhancing the speed and accuracy of updating asbuilt BIMs using Visual Programming (VP) and point-cloud survey data, thereby addressing this critical problem. Our proposed workflow, tested through action research, retains design data whilst integrating construction position details, enabling a seamless correlation between the design model and the as-built model. The results indicated that our method successfully reduced the median distance to cloud-point in 31 out of 33 elements (93.94%), albeit with a slightly lower accuracy rate (97.16%) compared to the reference software (97.64%). Notably, our approach significantly expedited the process, with an average processing time of less than a minute per face of element tested. These findings underscore the potential of the proposed workflow to improve the efficiency and precision of as-built BIM updates, providing a promising foundation for future enhancements and further research. Keywords ̶ BIM, As-built model, Visual programming, Dynamo, point-cloud, Laser scanning.
I INTRODUCTION In the BIM life cycle, the appointed party must deliver the as-built model to the appointing party at the end of the Collaborative Production phase [1]. When the asbuilt model is updated during the construction phase and it can be advantageous for numerous purposes such as design coordination, progress tracking, update quantity take-off and checking construction deviations from design. This data flow trails a sequence of design, check, build, as-built model updating, share information and coordination check. It might lead to a design or construction review (Fig. 1).
Fig. 1 – As-built data flow during the construction phase.
To be compatible for analysis and review, the model needs to be composed of parametric elements and Level of Detail (LOD) consistent with
the Exchange Information Requirements (EIR) [2]. The speed and accuracy of this data flow is essential to keep the construction schedule and quality of information [3]. This information will be shared through the Common data Environment (CDE) with multiple stakeholders, each one will run analyses for quality assurance check purposes and design coordination [1]. The accuracy and time spent on checking, updating, and sharing the as-built model information, depends on the technology adopted for realty capture and the methodology to translate this data into useful information for the team. Technology and methodology will be essential for the quality of the asset information model handed over at the end of the project [1]. To gather good quality data, companies are using technologies such as Total Station (TS), Photogrammetry and Terrestrial Laser Scanning (TLS) [4]. The TLS is considered the most accurate way to site survey for construction nowadays. It creates a dense 3D point-cloud file to represent the reality on site. Processing this immense amount of data and populating this information into the as-built model presents a huge challenge, is time-consuming and prone to errors [5]. To process this data, there are five main different methodologies as human visual checking (HVC), which overlap the design model against the survey, it relies on human judgment to determine the
The Proceedings CitA BIM Gathering Conference 2023 Page 24