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Geomatic Assessment WINTER 2017/18 GEOMATIC ASSESSMENT NC AWWA-WEA 3725 National Drive, Suite 217 •2 2018018 MembershipMembership DDirectoryirectory & Buyers’Buyers’ GuideGuide Raleigh, NC 27612 ADDRESS SERVICE REQUESTED • 9 97th7th AAnnualnnual CConferenceonference RRecapecap The official publication of the North Carolina Section of the American Water Works Association (NC AWWA) & the North Carolina Member Association of the Water Environment Federation (NC WEA) GEOMATIC ASSESSMENT How Unmanned Aerial Systems Are Changing the Surveying Industry: Comparing Real-World Accuracy and Cost with Traditional Survey Technologies By Christian Stallings, CP, Research & Development Manager, McKim & Creed, Inc. s a drone the best way to collect above ground to collect data at an developer. These types of surveys are data for your project? Unmanned accuracy of 5-cm root-mean square-error typically conducted using fixed-wing I aerial systems (UAS), aka drones, are (RMSE) or better. aerial photogrammetry, aerial lidar, certainly among the newest geomatics But is UAS right for every surveying and/or conventional ground surveying. technologies in the industry. UAS offers situation? In this article we describe three safe, accurate, cost-effective data case studies in which UAS technology UAS for Landfill Survey collection in areas that are inaccessible was compared with conventional To test the efficacy of using UAS technol- or too costly for conventional surveying surveying methods. We focused on ogy for volumetric surveys, McKim & Creed methods. Licensed and insured UAS three applications: a landfill volumetric teamed with landfill engineers Garrett pilots can legally deploy airframes into survey, a beach monitoring survey, and & Moore, Inc. to survey a 60-acre land FAA-controlled airspace up to 400 feet an elevation verification for a private clearing and inert debris landfill. Garrett & 58 NC Currents Winter 2017/18 Click Here to return to Table of Contents DEM with contours from the landfill site that was surveyed using UAS. The surface model created from the UAS-collected data of the landfill. Moore typically relies on aerial mapping unreliable in highly vegetated areas. data was compared for accuracy, cost, data to perform volumetric analyses. Using In those types of conditions, it may be and delivery time. a 3D Robotics Solo platform equipped necessary to supplement UAS with McKim & Creed again used our 3D with a Sony QX1 camera, McKim & Creed ground survey. Robotics’ Solo platform, along with SiteScan captured the data in less than an hour. software, for data collection. Esri processed The data was verified onsite, and point UAS for Beach Monitoring the data using its Drone2Map software. cloud creation was completed in less than During 2016 National Hurricane 24 hours. Planimetrics, contours, and Preparedness Week, McKim & Creed Results volumetrics were processed faster than teamed with geospatial software giant Esri The data comparison showed that, in the with conventional ground survey, aerial to conduct a proof of concept (POC) for correct environmental conditions – such photogrammetry, or lidar. local, state, and federal public agencies. as open beaches or moderately vegetated The project was designed to meet UAS was used to collect topographic data berms and basins – UAS outperformed ASRPS Positional Accuracy Standards for for beach monitoring surveys, which was conventional services by producing a more Digital geospatial Data (2014) for a 5cm then matched against conventional land detailed digital elevation model (DEM) RMSEz vertical Accuracy Class, equating survey data and terrestrial lidar data. The more quickly and at a lower cost. In fact, to Non-vegetated Vertical Accuracy =+/- 9.8 cm at 95%. Our results were twice that, at 2.25cm Vertical RSME, equating to 4.45cm at a 95% confidence level. We set eight control tiles prior to the flight and collected 12 independent ground truthing shots randomly throughout the project limits. These were compared to the post- processed 3D surface to measure the delta on the three axis from the known point to the drone survey. Results This project indicated that UAS can provide significant cost savings while exceeding the accuracy specification for this type of survey. Our results showed that, on average, using UAS for landfill surveys is approximately 10-40% cheaper than conventional ground survey based on the condition of the site, 30-40% cheaper than aerial photogrammetry, and 40-50% cheaper than lidar. A north-south flight pattern was chosen for the landfill with a forward overlap of 78% and a side overlap of 60%. UAS does have some drawbacks, The mission was flown at 400 ft. above ground level, giving a ground sampling distance of approximately 3.5 cm. Due to temperature and wind conditions, two flights were conducted to ensure proper battery failsafe. Flight 1 however. Data is difficult to capture and (in green) included 108 images, while 98 images were collected during Flight 2 (yellow). www.ncsafewater.org 59 Click Here to return to Table of Contents GEOMATIC ASSESSMENT “One other significant benefit specific to coastal monitoring is the ability for the UAS team to collect massive amounts of data in a short period of time. In the event of a major storm, a UAS survey can be accomplished just days before an approaching storm and McKim & Creed and Esri conducted a POC to test the accuracy, efficiency, cost effectiveness and again immediately after environmental efficacy of using low-cost, commercial unmanned aerial systems (UAS) for beach monitoring surveys. Here, McKim & Creed’s Christian Stallings, Certified Photogrammetrist (yellow vest) explains the UAS the storm subsides.” technology to representatives from local, state and federal agencies, as well as UNC Wilmington, Audubon Society and NC Land Trust. we estimated a 60% savings in time and event of a major storm, a UAS survey UAS for Earthwork Overages cost when compared to conventional can be accomplished just days before an Briar Chapel is a 1,600-acre master- techniques for the site. approaching storm and again immediately planned community in Chapel Hill, North One other significant benefit specific after the storm subsides. In addition to the Carolina, and is being developed by to coastal monitoring is the ability for the DEM, the UAS has the added benefit of Newland Communities. When the initial UAS team to collect massive amounts documenting the site with high-resolution clearing was completed on a 25-acre of data in a short period of time. In the (1.5cm) ortho photography. commercial site within Briar Chapel, This image was created so that Newland could visualize both the contours, as well as the high-resolution ortho. Inset: At 5 cm, the ortho showed exquisite detail. Capturing the data using conventional surveying methods would have taken approximately two days in the field with a two-person The data was processed in Esri’s Drone2Map software. Blue dots represent the location where each crew. UAS captured this same data in a few hours with the image was taken and the 3D model is laid over existing imagery. help of a one-person crew to provide ground-control points. 60 NC Currents Winter 2017/18 Click Here to return to Table of Contents The test site included two rock jetties. The inset is the 3D model produced from the UAS data, and the background image is a photo of the jetty taken by the drone. surveyors were asked to verify elevations. too long and be too expensive. And on we were trying to find another way to An aerial photogrammetry survey of the the ground, it would take two field crews be more efficient, manage the whole entire community site had been conducted approximately two days to collect the design-build process, and be integrative. by another company several years earlier, data. “We saw an opportunity to try out Hopefully it would be quicker,” said and the accuracies required verification. drone capabilities in our type of industry. Lee Bowman, senior project manager In their field checks, the surveyors In our partnership with McKim & Creed, with Newland. discovered some variances, ranging from a few inches to over a foot, between their data and the existing aerial survey. The discrepancies were not consistently low or high, they were just varied. And because the original aerial survey was done with full tree cover, which can sometimes skew survey data, the result was probably within originally- contracted tolerances. Even so, once construction began, the slight differences on paper could quickly turn into mountains of wasted dirt. Flying the site to collect new data would take www.ncsafewater.org 61 Click Here to return to Table of Contents GEOMATIC ASSESSMENT “Like its mobile counterpart, aerial lidar offers the benefits of fast, safe, and accurate data collection for wide area mapping and utility corridor mapping.” Other Innovative Data Collection Technologies Robotics Next-generation robotic total stations enable surveyors to use one- or two-person crews, rather than two- or three-person crews. The instruments feature integrated cameras that allow the photography to be georeferenced and used for mapping. This is a huge benefit to the CAD designer when drawing a map, and is a valuable QA/QC tool when checking for missed information. Mobile Lidar Mobile lidar is one of the safest methods of data collection around, provided you’re surveying in an area that’s navigable by a motorized vehicle. Mobile lidar can collect up to one million points per second, while traveling at posted speed limits. For urban highway design projects with multi-lanes and high-traffic areas, it is hands down the go-to system. The post processed data is accurate to within 0.05-ft. The system is highly flexible as well, and can be transferred to an ATV or boat to collect data in less accessible areas. Chad Burchette conducts a test run of one of McKim & Creed’s robotic total stations, which can enable Aerial Lidar surveyors to use one- or two-person crews, rather than two- or three-person crews.
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