On one recent Texas DOT project, SAM scanned 48 miles of highway. Ultimately, it was a hybrid job, with terrestrial lasers collecting data beneath overpasses and conventional survey setting control points, although airborne scanners accomplished the bulk of the work. Currently, the agency has developed contract specifications for more such projects. "This was the first airborne [scanned] highway," McNease says.
McNease says his team ran a cost comparison, exclusive of the traffic control costs. Based on traditional methods, the project had a $640,000 survey-mapping budget. Using the hybrid tool set, the final price tag came in at $400,000. Further, McNease's team only had five field crew days, compared to the 100 field crew days a conventional approach would have required. Post-collection processing time and cost was about the same.
McNease says another "key attraction" for Texas DOT was safety, as airborne scanning eliminates the need for people to work in a traffic-managed environment. "With traditional surveying, we would have to do lane closings and work in a very dangerous environment, plus delay people on their commute," he says.
"You've got to get your toe in the water, or [technology] is going to leave you behind," McNease adds. "Complacency has no place in construction. Complacency will put you out of business."
Technology Drivers
In late September 2011, Lake Mary, Fla.-based Faro Technologies Inc. introduced its new Focus 3D laser scanner, which is offered at less than half the cost of its $100,000 predecessors. It has a full set of advanced technological features, yet is engineered for ease of operation and mass production. Other innovations and offerings that are driving the market include:
• Advances in software and services for processing, hosting and vending scan data. Bentley Systems Inc., Exton, Pa., released at the show a new version of its Descartes V8i 3D modeling manipulation tool that now combines point clouds, raster imagery and geometry to support hybrid workflows. It leverages the PointTools point-cloud management and processing engine Bentley acquired last fall. The Bentley release is but the latest in a flood of recent moves by software vendors seeking to serve the scan market.
• Advances in automating the field integration—or registration—of scan data captured from multiple vantage points into a single point-cloud model. By being able to pull all the scans together while still in the field, operators can be sure all the required data has been collected before leaving the site.
• Advances in inertial measuring units, or IMUs, which accurately keep track of a moving scanner's changing position relative to a target registration point as it is moved, even from floor to floor by elevator. Some IMUs are so sensitive that they are on the government's export restriction list because they can be converted into missile guidance systems. Sophisticated IMUs are making it practical to use mobile equipment to work in global positioning system-denied environments, such as inside plants and buildings.
• Advances in mobility. Mobile scan data collection is all the rage and accuracy is improving, although there is debate over exactly what "mobility" means. Nearly every scanner at the trade show was at least mounted on a wheeled tripod, if not a rolling cart, a programmable robot, a truck or an ultralight aircraft. Many transport platforms are engineered to incorporate multiple measuring and data acquisition devices from several vendors simultaneously, but the debate centers on whether "mobile" should cover any scanning device that is easily moved but anchored on a point for scans or only cover scanners that are designed to collect data and self-map their environment while in motion.
