Speedy data acquisition; accurate, highly detailed data; and worker safety with minimal disruption to the public during surveying are all helping to increase the use of 3D laser scanning in civil engineering projects, according to laser scanning experts. “3D laser scanning has been shown to reduce engineering work load, improve overall accuracy of the work product — not just metric accuracy, but completeness as well — and improve communications between the designers, the owners, and construction personnel,” said Eric Hoffman, founder of Quantapoint, Inc., a laser scanning technology and services provider.
Improved integration between data collection technologies and engineering design software applications and the move to intelligent design models are also impacting acceptance and use. “The building information modeling (BIM) movement is having a large effect on bringing civil engineering into the intelligent 3D domain,” Hoffman said. “To be effective with BIM, you need rich and accurate 3D content of the existing conditions.”
Getting the data
Applications exhibiting the greatest increases in the use of 3D laser scanning include transportation infrastructure construction and management, according to most of the experts contacted for this article. Among the reasons for this is the acceptance of the technology as a valid survey method for data collection. “A large number of state and federal authorities have ratified the use of 3D laser scanning on government-funded projects,” said Bryan Williams, market manager for spatial imaging for Trimble. “On some projects, use of the technology is now mandatory.”
Other reasons for acceptance of the technology, according to Williams, are financial needs to complete projects within smaller budgets, efforts to increase overall productivity of existing or smaller crews; and pressures to meet tight project timelines and increased accountability for large publicly funded projects to deliver information, such as as-builts, in near real-time. In addition, survey and engineering firms are facing stiff competition for fewer projects, so these organizations are looking for ways to differentiate their capabilities as well as address projects and new opportunities in different ways, Williams said.
Scott Langbein, senior product manager for Topcon Positioning Systems, noted that the data accuracy provided by 3D laser scanning also translates into project cost savings. “We see a lot of increased use of laser scanners in volume analysis of construction activity and mining,” he said. “In today’s economic condition, making a better volume analysis of an expensive material makes better business sense. We have shown users how a laser-scanned volume can be more accurate by 10 percent or more. In today’s tight bidding results, a 10-percent bust on material costs can win a job.”
So, scanner manufacturers are focusing, in part, on helping civil engineers obtain more accurate survey data easier and faster, and in a more usable form. “Topcon laser scanner products are focused on ‘clean’ scan data and easily transportable hardware,” Langbein said. “Simply recording 5 million points is not our goal. Our products measure a surface and produce a result with little point cloud error in the measurements. A clean set of data allows for faster office modeling.”
Trimble’s SureScan technology is also designed to improve the quality of data capture. “SureScan will maintain [an] equal user-defined density of points, even for target objects such as roads and tunnels where distances to points vary,” Williams said. “Users won’t capture too many points at short distances and too few points at longer distances. SureScan makes both data collection and data processing faster.”
Additionally, “Trimble is focused on using a combination of 3D scanning, imaging, and traditional optics technologies coupled with specialized software workflows to make it easier for surveyors and civil engineers to take advantage of the productivity gains and expanded deliverables that can be created with spatial imaging,” Williams said.
That combination of technologies enables the Trimble VX Spatial Station to provide more comprehensive information quickly, while using measurement methods familiar to surveyors, according to Williams. And, it provides surveyors with a flexible solution to not only provide traditional surveying services such as site layout and as-built verification, but also the ability to improve productivity and provide additional project information with the use of imagery and 3D scanning in the same instrument.
Riegl USA, Inc., recently introduced a high-speed mobile 3D laser scanning system — the Riegl VMX-250 — that can operate at highway speeds, collect 600,000 measurements per second, and, according to Riegl USA President James H. Van Rens, completely revolutionize how transportation systems are surveyed. “A typical 10-mile road takes at least 10 weeks with traditional survey methods and it now can be done in a matter of hours,” Van Rens said. The VMX-250 is a multi-sensor system incorporating Lidar, realtime positioning systems, and photogrammetry. The output is a survey-grade, 3D point cloud in a common coordinate system, the company said.
“It is important to realize that the point cloud data is simply a medium of real world geometry,” Van Rens said. “That is its significance! The work flows must then take the point cloud information and transform them into traditional deliverables.”
Civil engineering firms and surveyors considering 3D laser scanning face two key challenges, according to Trimble’s Williams: training time to learn the new technology and office processing time to take vast amounts of data and turn it into client deliverables. “Advances in faster 3D scanners can exacerbate the latter issue, creating more points faster, not necessarily capturing the right points needed for the job,” he said.
Out of the point cloud
To help reduce office processing time, Trimble recently introduced a new software program called Trimble Access for Spatial Imaging, which is designed for rapid results in the field for faster deliverable times. “With the power to review, edit, and create deliverables at the job site, users can even deliver final results to customers from the field, dramatically reducing the need for complex and time-consuming office processing,” Williams said.
Topcon also offers ScanMaster software for file transfer of point cloud data into many third-party modeling software programs. “Engineering firms have chosen their CAD environment, such as AutoCAD or Microstation,” Topcon’s Langbein said. “However, there are many add-on packages available to better manage these large amounts of scan data.”
According to Ronald Gant, global marketing director for Bentley Systems, Inc., “Many data acquisition specialists are developing methods for characterizing laser data. An example is the application of photogrammetric techniques to laser scanned data by capturing stereo pairs or Lidargammetry. This technology makes it easier to ‘featurize’ or to provide intelligence to captured data.”
According to Van Rens, however, processing of the data is now being accomplished within the CAD programs, so the “middleware” point cloud processing software is receding in importance and use. For example, Bentley recently entered into a technology agreement to incorporate Pointools Ltd.’s Vortex API engine into Micro-Station and all other software products that leverage Bentley’s platform technology. Vortex API can reference and geospatially coordinate point cloud files captured by 3D laser scanning and aerial Lidar surveys.
“Bentley’s ProjectWise Navigator with its i-model file format enables users to aggregate 2D and 3D multi-discipline geometry in the same file for concurrent review,” Gant said. “ProjectWise Navigator makes clash detection, object avoidance, and model verification fast, simple, and easy.”
And in October, Autodesk announced that its Subscription Advantage Pack for Civil 3D includes a new point cloud capability. According to Pete Kelsey, key accounts technical manager for Autodesk AEC Solutions, the point cloud feature enables users to import Lidar data in LAS format and all point file formats supported by AutoCAD Civil 3D 2010; visualize large point clouds in 3D; stylize point data based on LAS classifications, RGB, elevation, and intensity; filter point data by style; and snap to points within the point cloud using standard AutoCAD software tools.
“Prior to this enhancement, civil engineers had to use third-party applications to import point cloud data into Civil 3D, and it was very time consuming,” said Kelsey. “The challenge was always how to import gigabytes of cloud data without having the receiving CAD application not lock up. You would typically have to cut up your cloud data into more manageable pieces … ‘dumbing down’ the rich data, and weeding it down to something much smaller.”
Carlson Software offers the Carlson Pointcloud module working inside Autocad and Intellicad. “This product can handle source files from Leica, Riegl, Optech, Faro, and other popular scanners, and will conduct registration (the stitching together of multiple scans),” said Bruce Carlson, president of Carlson Software. “The Pointcloud module has strong 3D viewing and can handle clouds of up to 1 billion points, and through processes of decimation, data extraction, and field-to-finish, can create plan view drawings, profiles, sections, contour maps, DTM surfaces, and other deliverables, all within the most popular CAD environments.”
According to Kelsey, Autodesk is also researching how 3D design models can be combined with point cloud data in a model aggregation environment (made possible by a tool such as Navisworks) to perform clash detection and other analysis. “Laser scanners, the point cloud data they generate, and the incorporation of this data to create highly accurate 3D models are literally changing the surveying industry, and in turn, civil engineering overall,” he said.
For example, according to Carlson, new applications are being explored in the area of highway design, including road intersection mapping and even road resurfacing. “For example,” he said, “scanning can identify precise rutting and subsidence conditions on roads leading to strategic designs that optimize milling and repaving work. For these applications, scanning can lead to designs that feed machine control, for ultimate efficiencies.”
Scanning technology has far outpaced the downstream automation associated with software processing,” Carlson said. “But the ability of software to filter out extraneous, unwanted data, auto-detect breaklines, and assist in drawing line-work and symbols is expanding at a rapid pace and will ultimately dictate when scanning goes mainstream within the civil engineering community.”
Of course, the cost of this high-tech equipment will also dictate how rapidly civil engineering firms adopt 3D laser scanning. “A significant impact to the use of laser scanning in civil engineering is the investment required and that return on investment,” admitted Langbein. But he predicted that users will continue to see lower prices for laser scanning systems as companies focus on manufacturing instruments at lower costs, while maintaining high performance.