by Michael Tardif, Assoc. AIA
Contributing Editor

Summary: While we tend to think of building information modeling (BIM) as the “core of the revolution” in design technology, there are other, related technologies with the potential to change significantly the way buildings are designed and constructed, and that, in turn, may have a significant impact on decisions that building owners make about the built environment.

Three-dimensional laser scanning of existing buildings is one technology whose development has paralleled—more or less independently—the development of BIM. The opportunities for convergence of these technologies, which may seem obvious, are only now beginning to occur and can be expected to accelerate rapidly in the next few years, as building owners, design professionals, and constructors continually increase their knowledge of these tools and find new ways to exploit them. By reducing the cost and time needed to document existing buildings while dramatically improving the quality and detail of the documentation, 3D laser scanning may inspire building owners to view the rehabilitation, adaptive reuse, or historic preservation of existing buildings more favorably.

Conceptually, 3D laser scanning is as simple as it sounds. A 3D laser scanner is placed in the center of an interior space and scans the interior surfaces with a laser beam, generating a three-dimensional “point cloud” data file that can then be converted to 2D CAD, 3D BIM, or even black and white photographic images. The technology is equally useful for documenting building exteriors as well as interior spaces that might be too small to be physically accessible or may contain hazardous materials, such as interstitial spaces with asbestos insulation. Most often cited for documenting historic structures with a high level of exterior or interior architectural detail, 3D laser scanning can be used to document any existing building of any age and style for which accurate existing condition documentation is needed.

Case study: Martinez & Johnson Architecture
Martinez & Johnson Architecture of Washington, D.C., a firm that has developed a design specialty in the rehabilitation or historic preservation of commercial, residential, and performing arts buildings, has been using laser scanning for years, in the process amassing a dramatic design portfolio that includes some of the finest restored performing arts venues in the country. Though the raw data format of a 3D laser scan—the point cloud data—can be readily converted into any number of CAD and BIM data formats, Martinez & Johnson, having completed eight complex projects in the past 18 months with lead times ranging from 2–10 years, is only now finding the time to thoughtfully make the transition to BIM.

“These projects have brought us through a learning curve,” notes firm principal Tom Johnson, AIA. “I was slow to convert to laser scanning. The typical owner/architect contract requires the owner to provide base building information, but the reality of rehabilitation projects is that architects usually do it. Laser scanning provides us with the highest quality of base building information.” The firm plans to follow the model of other firms that have made the CAD-to-BIM transition successfully by choosing a new project to serve as a BIM pilot, which can then be analyzed to tailor new BIM design and business processes to the firm’s specialized work. “We’ve been sending staff to training in waves,” says Johnson. “The next project that goes into production, we’ll be ready for BIM.”

Accurate record of details
The firm has found that 3D laser scanning is useful to clients beyond providing base information for design. “Projects that involve federal tax credits for historic preservation have a high level of regulatory review,” says Johnson. “The laser scan provides assurance that we are recording details, including existing conditions and defects.” The extensive documentation helps assure regulatory authorities and other historic preservation stakeholders that the historic fabric of a building has been retained and preserved to the maximum degree possible. Photographic images generated from scans can also be used to depict and define the scope of rehabilitation work more clearly for contractors than is possible with conventional drawings and specifications.

The firm’s experience has caught the attention of the Office of the Chief Architect of the U.S. General Services Administration, a building owner with a greater-than-typical need for accurate documentation of existing buildings. The firm is currently working on a GSA project involving the restoration/rehabilitation of the federal courthouse in Brooklyn, N.Y. “There are a number of ways to measure existing buildings,” says Johnson. “When we responded to the GSA RFP, we were the first firm they had seen that had been using laser scanning for so long.”

Copyright 2007 Michael Tardif
Reprinted with permission.