Reconstructing Buildings from Physical Facilities into Virtual Realities
In November 2008 Clark Construction and joint venture partner Hunt Construction Group were awarded a contract for building phase IV of the VA Southern Nevada Healthcare System’s new 150-acre medical campus. At $364.9 million, the hospital project was the largest ever awarded by the VA.
Clark Construction is one of the largest general contracting companies in the United States and one of their primary tenets is their commitment to a well planned pre-construction phase. Extra care early on can lead to fewer construction-phase changes, reduced construction time, and cost savings. Their commitment to this principal has led them to embrace many cutting-edge technologies such as Building Information Modeling or BIM.
Associated General Contractors of America define BIM as “an object-oriented building development tool that utilizes 5-D modeling concepts, information technology and software interoperability to design, construct and operate a building project, as well as communicate its details.”
According to Jim Day, Vice President of the Las Vegas Office, in an interview with Business Excellence Magazine, the biggest advantage to BIM is “improved efficiency when you get to the point where you are installing systems.” Pre-BIM, spatial conflicts during installation might not have been detected until systems were being installed; with a Building Information Model these errors (and the time and costs associated with them) can be avoided.
During the construction planning phase for the hospital, the team at Clark encountered design challenges that could be solved using cutting-edge 3D laser scanning technologies. They were interested in including an existing energy plant into their VA Hospital BIM. Rather than attempt to create a model of the plant from scratch, Clark Construction was looking for a company who could document the existing rooms and model them into a format suitable for inclusion in their hospital model.
With over 15 years of experience with thousands of complex 3D measurement problems of virtually all type and size, Direct Dimensions was up to the task. Direct Dimensions team members Glenn Woodburn and Dan Haga flew out to the VA Hospital Site with a Faro LS Laser Scanner, a long-range, large-volume spherical scanner that can digitize vast open spaces with precision very quickly. Over the course of a week, they scanned and documented 10 extensive MEP spaces within the facility from multiple vantage points. These 3D laser scans included all existing facilities and installed components including mechanical, electrical, and plumbing fit-outs, air handling duct work, and structural ladders, catwalks, and platforms.
The scanner, mounted on a tripod like a camera, collected raw data in the form of a dense 3D spherical ‘point cloud’ of millions of coordinates of the elements within the facility. In the end, these 3D laser images formed a high-definition survey of each room, a process that could take weeks using conventional survey measurement tools.
Upon returning to the Direct Dimensions facility in Owings Mills, the raw data scans were loaded into PolyWorks software and then coordinated and aligned together to form single point clouds of each room. Even at this initial stage, measurements can be extracted from any location within the entire facility as if using a virtual tape measure.
After the scans were aligned in PolyWorks, they were brought into Rhino using the Pointools plug-in to create engineered geometry-based models. Then rooms that were spatially related, such as the boiler and chiller rooms, were aligned together for easier inclusion into the final BIM. The final CAD models were exported in DXF format, suitable for importation into NavisWorks, the software package Clark was using to construct the BIM.
Phase IV of the VA Southern Nevada Healthcare System’s new 150-acre medical campus is scheduled to be completed in 2011.
