Performing Classic As-builts with Laser Scanning

Adapted from a presentation made at the Leica HDS International User Group Meeting at San Ramon, CA, in November 2005

The move to adaptive reuse has represented quite a paradigm shift in the construction industry both in Los Angeles and across the country. The result has been a change in perception—new metropolitans want to live in an urban community where valuable old buildings are kept and reused, rather than bulldozed. In turn, that has caused a challenge to the construction and architectural industry in the United States, where there has been a core focus on new build. New skills and new approaches would have to be adopted to meet this challenge. Mollenhauer's answer to this was to provide accurate as-built data of large, often derelict, complicated and historic buildings that were being transformed into restaurants, lofts, and hotels—all enriching a revitalized environment.

Why Are As-built Data So Critical?

Accurate as-built data are critical components of the entire planning and design process. Often, there are no as-built records for buildings more than 30 years old, and when they do exist are most often hard copy blueprints that may have limited value for preservation, rehabilitation, restoration, or reconstruction efforts of historic buildings for adaptive reuse.

Important buildings, especially when they are of historic significance, are often subject to environmental review pursuant to state laws, such as the California Environmental Quality Act, which requires state, county, and city officials to consider the feasibility of treating historic buildings consistent with the specifications of The Secretary of the Interior's Standards for the Treatment of Historic Properties with Illustrated Guidelines for Preserving, Rehabilitating, Restoring, and Reconstructing Historic Buildings. Similarly, on projects involving federal lands or the use of federal funds, environmental review is required pursuant to Section 106 of the National Historic Preservation Act. Accurate as-built drawings are an essential tool in understanding the original construction and character of a historic building, assessing the feasibility of structural upgrade and seismic retrofit to support adaptive reuse of a building, and in defining the period of significance, and character-defining construction and architectural features of the building.

The architect and engineers armed with this comprehensive analytical tool can now make better informed intervention and design decisions for the future of the building. The architectural computer-aided design (CAD) data are the foundation of the construction documents. Finally, as-built data are being used increasingly to initiate a facilities management tool for the long-term management of the asset, whereby databases can be integrated through growing use of a Building Information Model (B.I.M)—an easily usable data storehouse that simulates building system behavior in a virtual 3D environment.

What Happens?

An article in the January 2003 edition of The Economist, reporting on the current state of the construction industry, stated that "Inefficiencies, mistakes and delays account for $200 billion of the $650 billion spent on construction every year," a staggering amount due to bad practice and wastage. In the survey process identified by the article, replication of effort has added significantly to those statistics. As an example, separate surveys are often carried out independently for the feasibility analysis, environmental review process, the materials condition assessment, and the structural review. Furthermore, the construction documents can be drafted from existing copies of blueprint drawings, with site changes added where possible, with little consideration to accuracy. However, this is not a very effective way to do work. Adjustments needed to remedy the inaccuracies often lead to time and money wasted in mitigation and a culture of change orders.

Model Project

Mollenhauer was approached by Sapphos Environmental, Inc. of Pasadena, California, pursuant to their contract with the County of Los Angeles Chief Administrative Office, to use new high-definition scanning technology to produce a record for the Plaza de Cultura y Arte project, which includes an ensemble of three historic buildings that had been vacant for several decades and suffered deterioration related to both man-made and natural elements.

Spatial Geomatics made a successful presentation to the County of Los Angeles, communicating the value of a consolidated strategic approach. The approach provided benefits to the County as a long-term asset manager by providing an accurate set of comprehensive building data to carry out the required analysis and to plan the best uses of the buildings. The data would also meet the requirement to produce an archive record for the Department of the Interior's Historic American Buildings Survey (HABS) as an inventory of the structures.

The use of the laser scanner is ideal wherever there are issues of safety, access, or complexity. This Project exemplified all of those characteristics—the interiors had spaces where the floor was weak and dangerous, the interiors were dark, and, most of all, the structures and the facades were very complicated. The Leica HDS 3000 was used to record all of the exteriors, the roof spaces, large areas of complexity, and interior areas that are difficult to access. The scan survey was supported by control and interior data collected by Mollenhauer's conventional survey teams using standard total stations, as well as by a hand survey using tape and disto. Cyclone was used to register all of the point cloud data, which was exported to AutoCAD, using Cloudworx. All the data were brought together in a 3D CAD world—using Maya—and wireframes and fly-throughs were created. The County of Los Angeles was presented with a comprehensive set of accurate as-built data, including elevations, vertical sections, and floor plans, all generated from the 3D data, and all totally reliable. The data were used immediately to determine the structures' stabilization and shoring. The County provided the data to the architects selected for the project, and used the data to generate all of the construction drawings.

Results

The data generated through this approach has been useful in the design development and regulatory compliance processes. There is no doubt that an accurate, detailed 3D survey is expensive and requires a leap in faith. But the approach, a more strategic approach to data collection and management, has been justified and rewarded. For an owner of a property portfolio and for an institutional client like the County of Los Angeles, this approach will show a projected 200% return on investment over time through not having to replicate survey collection. Mollenhauer Group is currently working with the County of Los Angeles and Sapphos Environmental, Inc. to assess the feasibility of utilizing this technology on other complex projects involving multiple historic buildings. Also being explored is the ability to maintain long-term accessibility to the point cloud out using an integrated database.

Conclusion

This project verified the potential for significant cost savings and strategic advantage associated with a one-time collection of very accurate 3D as-built data for a major adaptive reuse project, which can be repurposed for all of the project's needs—right through to the potential of a BIM for the lifetime of the buildings.

The Future

The market for this kind of survey is not yet mature, and clients have been slow to adopt this approach. Although significant inroads have been made since the inception of Spatial Geomatics some two years ago, much has to be done to educate the architects, owners, and engineers that a foundation of accurate 3D data is an investment in most complicated projects of commercial adaptive reuse—especially when there are issues of time, safety, or complexity. But we are optimistic of change, especially where there are more and more statutory requirements for more effective stewardship and long-term maintenance, all of which would benefit from an upfront investment in accurate as-built data.

In addition to the construction market—in adaptive reuse—Spatial Geomatics is actively pursuing our local industry, The Movies—especially visual effects—where the need and understanding of 3D mesh data are definitely growing and becoming the norm. The technology can be used for scanning movie sets, planning match moves, scouting a location, or taking the whole of a city environment and moving it in a virtual world to a new location. In a computer-generated imagery (CGI) world, there will definitely be a growth in this industry—the new challenge is integrating the rigors of working in the construction industry to the SWAT team approach of the movie community.

Of course, there is a variety of uses for the data beyond construction. One of our last projects was to map the world famous footprints and handprints of the Mann's Chinese Theatre on Hollywood Boulevard, where the 3D data are being used to carry out important renovations to the site and help manage future activities. When the marketing staff saw the data, they were blown away and are now actively looking to see how they can use the data for their website and marketing materials. The 3D data can be used for marketing, education, information, and presentations.

Acknowledgments

Thanks to Sapphos Environmental, Inc. and the County of Los Angeles for the use of the data and their innovative approach to the use of 3D data for management.

About the Author

Christopher Gray is the Historic Building Preservation Specialist with Mollenhauer Group of Los Angeles. His 20-year career combines extensive experience in England and the U.S. with knowledge of the state-of-the-art technology of 3D laser scanning.

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