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State transportation agencies today are in a bind. Federal regulations require data-driven decision making aimed at maximizing the benefit of investments and improving long-term performance and safety for the public, while state budgets are placing increasing pressure on agencies to reduce costs and turnaround times. Mobile mapping technology is highly suitable for these applications, as well as design-build projects, accident investigations, security, and others. However, cost-effectiveness and flexibility have not been strong points of traditional mobile mapping systems.
There are two distinct categories of mobile mapping today: (1) video logging and asset inventory, and (2) surveygrade map generation. The first category involves the collection of features without recording precise location, so the process is faster and less expensive than the latter, which produces highly accurate and comprehensive deliverables that can be prohibitively expensive for mapping large areas. Over the past few years, mobile mapping devices have rapidly evolved to offer multiple types of data collection at higher speeds with greater accuracy, but the high cost of these devices combined with the amount of time required for post-processing to achieve survey-grade data have remained major obstacles to their widespread adoption.
Seeking a More Efficient Solution
Looking for a way to break down these barriers, transportation agencies and service providers have been eyeing the Leica Pegasus:One mobile mapping solution with interest. Introduced by Leica Geosystems in June 2013, the Pegasus:One combines integrated and configurable components to provide a versatile mobile mapping solution designed to meet the needs of both inventory-grade and survey-grade mapping projects.
The basic system includes NovAtel SPAN technology, which connects a precise GNSS receiver with a robust IMU to provide the system with a position accuracy of 2 cm RMS even after 10 seconds of outage, as well as six 2MB cameras positioned to capture digital imagery at a full 360 x 70 degree view. From there, users can configure the LiDAR component to meet their needs. Firms and agencies that have invested in terrestrial laser scanning can use the Leica ScanStation P20 in a plug-and-play configuration that provides the flexibility to use the same scanner for both stationary scanning and mobile mapping. Alternatively, firms desiring a dedicated mobile mapping solution typically specify the Z+F 9012 Profiler running at 200Hz (1.1 million points per second) as a permanent part of the system.
For added versatility, the Pegasus:One is compact and portable and can be mounted on a boat, ATV, or vehicle depending on the project requirements.
This combination of features brings new capabilities to mobile mapping. "The Pegasus:One is unique in that it achieves absolute accuracy of +/- 2 cm at the 95% confidence level, without ground control, at normal driving speed," said Bradley Adams, PE, mobile mapping manager for Leica Geosystems. "The speed at which we can drive translates into more volume of data collected in a day, and the best part is we get survey-grade data and asset-grade data simultaneously. The time savings is significant."
What a Difference the Software Makes
The Pegasus:One uses ArcGDS software, an extension of ArcGIS that allows Esri users to use stereoscopic images and the LiDAR data for the acquisition, editing and updating of 3D features directly within the Esri environment. In creating the software, developers focused on improving the ability to process and share data quickly. The industry standard until now has been approximately five to six days of processing for every one day of collection. A test run with the Pegasus:One in Dallas involved the collection of 30 miles of data in 3 hours, and the data was ready in just four hours. Service providers have experienced a similar one-to-one ratio of data collection and processing time on real-world projects. According to Adams, this reduction in processing time has a significant impact on the duration of projects and the timeliness of obtaining usable information.
Other features help prevent rework, such as a mini-PC inside the vehicle that gives a real-time view from every camera, and a Google Street View style interface that allows office staff to assess quality of data within 30 minutes. The imagery and point cloud are calibrated together, so clicking in one data set immediately provides access to the other, and the point cloud can be colorized for easy visualization. ArcGDS also displays the trajectory and map in a free viewer that can be used by clients for preliminary navigation and exploration of the data.
"The real differentiators for the Pegasus:One are the speed with which it collects and processes the data and the speed with which the data can be post-processed," said Adams. "It is unheard of to offer a one-to-one ratio of field collection to office time that results in such high-accuracy data. And the resulting integrated imagery and point cloud information that forms an overlay in Esri ArcMap allows us full use of comprehensive data and the ability to easily distribute and share with everyone, not just experienced users."
Expanding Business Opportunities
In October 2013, Spicer Group Inc., based in Saginaw, Mich., became the first professional engineering, land surveying and planning services firm in North America to purchase the Pegasus:One mobile mapping solution. As a full Leica shop with 26 Leica Geosystems GPS receivers and 13 robotic total stations, the firm’s focus on both engineering-grade surveys and municipal asset inventory and management made the new Leica Pegasus:One solution a perfect fit.
"After extensive vetting of all available survey-grade sensors, we selected the Leica Pegasus:One," said Eric S. Barden, PS, geospatial lead and partner at Spicer Group. "Accuracy was our number one priority, but we were also looking for a software solution that worked within our GIS that would allow us to successfully complete large-scale asset mapping projects. System portability to different collection platforms was also a key factor.
"For several years we had been investing in mobile mapping software and training our staff to process datasets collected by third party providers," Barden explained. "The mobile mapping business was growing and we decided to acquire our own resources. With the Pegasus:One we can do much larger transportation and utility corridor projects, at a much higher level of production with increased safety, which also means our clients are able to do larger projects than before. The collection is more cost effective than boots on the ground. For one recent project we put the unit on a boat to map a five-mile river corridor in less than a day, and we processed the data and produced a DTM surface of the river banks for the entire corridor. We completed in two weeks what would have otherwise taken six to eight weeks to complete by conventional surveying means."
The free Leica ArcGDS viewer allows users to see the imagery and LiDAR data within the Esri ArcGIS environment. "Most of our customers are Esri users, and they’re interested in accessing their data through ArcGIS and the ArcGDS Street View style interface to aid with design," said Barden. "Even inexperienced users can open the LiDAR data set, view the imagery and LiDAR together and obtain basic measurements."
Rice Associates, a complete geospatial services firm with offices in Manassas, Richmond, and Virginia Beach, Va., took delivery of a Pegasus:One in February 2014. During beta testing and training, the firm has received a number of inquiries from clients interested in design/build and asset management projects. "We feel strongly that having our own mobile mapping capabilities will open up new opportunities for the firm and our clients," said Charlie Rice, founder and president of Rice Associates. "In the past we’ve focused on photogrammetric and conventional survey services, but this device allows us to expand into asset management services. We’ve owned Leica terrestrial scanners and software since 2009, so this was a logical step for us to be able to provide this service to our clients."
For Rice, the software component was a big factor in the decision-making process. "The simplicity of the ArcGDS software as it relates to asset management is unique," he said. "Most mobile LiDAR collects millions of points and then you have to manually add a lot of features, but with Leica’s software the feature extraction is a three or four click operation. It is much more automated than comparable systems, which saves our clients time and money."
The versatility of the solution allows the firm to respond proactively to client needs. "Unlike aerial mapping, the mobile mapping system allows us to provide interim deliverables like preliminary topographic data right away to clients, and that is very important," concluded Rice. "We can do fill-in topography at a later date during postprocessing, but overall schedules are significantly reduced. And because the time and cost to obtain comprehensive datasets is reduced, updates are more feasible, which leads to repeat business with our clients."
In Texas, Fort Worth-based Gorrondona & Associates, Inc. (G&AI) is using the Pegasus:One on projects for the Texas Department of Transportation and also sees applications for municipalities, water districts and power companies. G&AI President Brad J. Gorrondona said the combination of innovative hardware, intuitive software and streamlined workflows allows the firm to provide clients with high quality and a fast turnaround at reasonable rates.
Can a single mobile mapping system do it all? Professionals in the surveying and mapping community believe it can. "The Pegasus:One provides incredible efficiency and impressive deliverables," Gorrondona said. "I haven’t seen anything else that even comes close in a LiDAR based format regarding both gathering of information and software capabilities."
Linda Duffy is president of Apropos Research, an independent market research firm that provides market research and marketing communications services to the geospatial and remote sensing community. For more information about mobile mapping solutions, visit www.leica-geosystems.us.
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