Scanning the Third Dimension

By Erin Fallon, CCE, PSP, CCCA

While the construction industry is often considered to be a slow adopter of new technology, design and construction professionals are challenging themselves to build projects faster and cheaper with the use of technologies like BIM, tablets, and custom-designed apps. A less publicized technology in the adoption phase is 3D laser scanning. Engineering and consulting firms are recognizing the benefits laser scanning can bring to their clients and operations.

What is 3D Laser Scanning?

3D laser scanning technology digitally captures the dimensions and spatial relationship of objects using a line of laser light. The scanner outputs a point cloud image, which accurately replicates the scanned objects. Depending on the type and make of the scanner, objects can be scanned from up to several hundred meters, and data points can be collected to the accuracy of less than 5mm at speeds from several thousand to several hundred thousand points per second. The overall speed depends on the desired density of the point cloud. When an object is too large to be captured in a single scan, multiple scans from different lines of sight can be linked together to complete the point cloud image. Once the 3D point cloud is generated, the data can be exported to many common CAD, modeling and BIM programs to generate 2D CAD drawings or a 3D model.

Primary Uses

Despite slow adoption, 3D scanning currently serves a number of purposes and is used in a variety of industries. 3D scanning uses range from roadway and bridge surveying to process plant maintenance and retrofit projects to bridge and building deformation monitoring. Some areas where 3D scanning is currently in use are discussed further below.

  • Transportation

3D scanning is used in the construction and maintenance of roadways and bridges, including road topography surveying, roadway surface and pavement profiling, paving volume calculations, intersection surveys, bridge design as-builts, bridge damage assessments and historical archiving. 3D scanning is also utilized in the maintenance and construction of tunnels, airports, rail, and ports and harbors.

  • Utilities & Process Plants

3D laser scanning can accurately document existing conditions of facilities to assist with minimizing conflicts between new and existing components during facility upgrade projects. 3D scanning also permits personnel to remotely view and evaluate facilities, limiting the number of personnel exposed to hazardous working conditions.

  • Building/Facility Renovation

It’s common to encounter incomplete or inaccurate as-built drawings for an existing building. 3D scans can be used to develop accurate 3D models of the interior and exterior of existing buildings, which can aide in planning and designing future additions and renovations.

  • Offshore Oil Production Facilities

Offshore oil production facilities require a high level of dimensional control throughout their lifecycle. The typical modular construction of offshore platforms requires tolerances to be closely managed between topside and underwater structures. Laser scanning can be used to validate the entire jobsite geometry. And in cases of storm damage, laser scanning can be a quicker and safer method for assessing damage.

  • Forensic Evaluation

3D scanning can assist with evidence preservation and forensic evaluation. Instead of relying upon photographic evidence and field measurements for forensic evaluations, 3D scanning can assist forensic engineers and legal teams to quickly and accurately preserve an accident scene and its evidence. Once the data is captured, it can be utilized to construct 3D models of the sceneuse during mediation, arbitration or litigation.

Reported Benefits

3D scanning might not cost less than traditional surveying methods, but in some cases the benefits outweigh the costs. “Scanning has been a tremendous addition to our services and allows us to obtain a level of detail that was not possible or feasible with other conventional survey methods,” states Paul LeBaron, Director of Land Surveying at Nitsch Engineering. “When used appropriately it can provide a higher level of detail, safe locations in hazardous areas, and save the team time by reducing the need to send a crew back to a site to obtain more locations. Our investment in the technology has paid off for both our firm and our clients who have taken advantage of its use.”

  • Improved Planning & Design

Point cloud based as-built drawings and 3D models can improve design by analyzing clashes between newly designed elements and existing conditions or by evaluating alternative designs prior to construction. The accurateness of dimensions obtained from laser scans can also help improve planning by providing exact measurements for demolition and removal of components, as well as for prefabricated materials, minimizing waste and changes in the field.

  • Safety & Regulatory Compliance

Laser scanning methods are often safer than manual data capture methods and are increasingly being used to help comply with health, safety and environmental imperatives. The remote sensing ability and quick data capture of laser scanners reduces a crew’s exposure to harmful environments. For example, 3D scanning can be used in completing land surveys without the need to stop one car. Furthermore, in nuclear power plants, laser scanning can help reduce the size of and the time crews are exposed to high radiation areas.

  • Cost & Schedule Reduction

It’s been reported that 3D scanning can reduce total project costs by as much as 5 – 7% and the schedule by as much as 10% on industrial projects. The scanning can take as little as a few hours to a few days, depending on the scale of the site, as compared to several weeks using traditional data collection methods. In some cases, the savings in time and in ancillary costs may outweigh the cost of the scanning.

  • Hindrances to Adoption

While the 3D scanning market has reportedly grown 25 – 30% over the last five years, the technology is still early in the adoption cycle. Because traditional surveying methods are more cost effective on some projects, it may be difficult to determine when to make the leap to laser scanning. If a company has not yet adopted designing and constructing in 3D, it may be difficult to “buy-in” to laser scanning. Lastly, like other 3D technologies in the marketplace, there are integration challenges involved with laser scanning. Some design solutions have embraced point cloud integration, while others have not.

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