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Current workflows employed for dimensional control compliance remain time-consuming, expensive, and unreliable (Bosché, Turkan, Haas, & Haas, 2010). Although use of laser scanning techniques is becoming more widespread, the automation of dimensional control compliance remains elusive to many practitioners. There exists a need for automated dimensional control compliance to assure that the built environment matches design models, and that as-built and record drawings and models match the physical reality. As industries try to escape from 2D flatland (Tufte, 1990) into the vast world of Building Information Modelling (BIM), traditional 2D Computer-Aided Design (CAD) workflows need to be re-established within 3D information rich virtual environments. These new BIM workflows have been evolving over the last few decades to provide integrity of design responsibility. New data exchange methods are also needed to assure integrity of design responsibility going forward. The research documented in this paper contributes an innovative solution to automated dimensional control compliance and the utilisation of open standard data exchange methods that supports design integrity and stakeholder responsibility.
To support such 3D workflows, the Industry Foundation Classes (IFC) and BIM Collaboration Format (BCF) are the media that should be used to formally communicate coordination issues that are to be resolved in virtual space. In traditional practice the relevant parties are responsible for modifying their design according to model element clash issues communicated to them by others, and this process is unchanged when using BCF with IFC. Disputes arise in poorly-implemented virtual construction and collaboration environments when practitioners assume liability to resolve issues that do not belong to them. This can be avoided if IFC and BCF are properly utilised to communicate and resolve design conflicts and interests.
Traditionally, the final contract deliverable includes a set of record drawings and/or marked-up red-line drawings. These traditional deliverables are most commonly achieved through subjective and expensive design validation processes performed manually by stakeholders. In more modern construction practices, Terrestrial Laser Scanning (TLS) hardware is commonly used on-site for surveying. The TLS hardware captures reality as data in the form of a “point cloud” (i.e., a collection of 3D points in space). Surveying methods like TLS afford major exploitations of the data gathered such as progress control, structural health monitoring, dimensional control, and as-built BIM modelling (Bosché & O’Keeffe, 2015). In this paper, the authors focus on best practices for communicating dimensional control compliance utilising point clouds and corresponding design BIMs. To date there has been no known standard method to automate the communication of the deviations and variances detected when performing dimensional control compliance. Current best practices are to overlay models with point clouds. The process of identifying and resolving issues remains a time-consuming, painstaking, costly, and ultimately subjective endeavour performed by individuals virtually “walking” through the building.
The authors have developed an objective and controlled process for identifying and reporting dimensional control compliance issues automatically. Using BCF, the responsible stakeholder is taken directly to a view of the issue(s) discovered. Additionally, this automated process provides explanations and suggestions to the requisite stakeholders on how the detected issues may be resolved. The paper’s focus in relation to dimensional control compliance is that when modelled structures are built, they are not always built exactly to the design. Often there are unrecorded field changes that cause variations between the real built environment and the virtual design model. To ensure ongoing spatial control of the physical build, scanning of completed building works allows for a methodology of identifying differences (i.e., Scan-vs-BIM; Bosché, Guillemet, Turkan, Haas, & Haas, 2014).