Launching a New Surveying Perspective

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2 Launching a New Surveying Perspective >> By Mary Jo Wagner A 3 km2 orthomosaic shows the entire construction site and surroundings. On the upper part of the mosaic are the Bristol Channel; the existing Hinkley Point A facilities are on the right.

3 It used to be that Rodolphe Jobard would assemble and fly remote-controlled airplanes in his spare time. Now, he is actually paid to do it. Jobard, a professional engineer with EDF Energy, can routinely be seen walking to the center of a massive, dirt-laden field, assembling a catapult and launching an unmanned aerial system (UAS) into the sky. It s a nearly weekly ritual that Jobard has been performing since last May as part of his project management tasks for EDF s expansion project at Hinkley Point nuclear power station in Somerset, England. I knew shortly after arriving on site that we would need aerial photography and conventional aerial surveying approaches would be a challenge, explains Jobard, EDF s aerial intelligence team leader and a qualified pilot. In particular, we re building near an existing nuclear power station, which presents airspace-access issues, and cloud cover is a constant problem. A UAS aerial surveying system would resolve both the airspace and cloud cover issues and enable us to have an overview of the Hinkley site as often as we need. And it was a ground-breaking decision it made Jobard the first-ever UAS user in EDF and in the United Kingdom, and a pioneer in the nuclear power industry that has shown its worth in the air and on the ground. Indeed, the UAS has not only proven to be the most efficient and effective means to map the site, it has become a core data source for many business applications. Size Matters Hinkley Point, near England s southwest coast, is one of eight nuclear power stations owned and operated by EDF, a wholly-owned subsidiary of France-based EDF Group, one of the three largest energy companies in Europe. The company generates around one-fifth of the UK s electricity and also supplies electricity and gas to about 5.5 million residential and business customers in the UK. With the UK facing an energy shortage 8 power stations are scheduled to close by 2023 EDF, in concert with the British government, identified Hinkley Point as a suitable site for a new nuclear power station. Designated Hinkley Point C, the new low-carbon nuclear plant will be constructed immediately to the west of the existing Hinkley Point B power station, which was built 38 years ago and is due for decommissioning in It will be the first new nuclear power plant to be built in the UK for 25 years. Comprising 150 hectares (370 acres), Hinkley Point C will have two new nuclear reactors capable of generating a total of up to 3,260 megawatts of electricity and providing low-carbon energy to around five million homes. Though the chosen site would enable EDF to capitalize on Hinkley B s existing energy infrastructure and access roads, the sheer expanse of the site posed significant planning and monitoring challenges. Although a conventional aerial survey was commissioned in late 2008, providing some aerial photos and orthomosaics of the site, Jobard knew the frequent cloud cover and high costs of routinely commissioning a full-sized aircraft would negate its viability as a routine information source. We wanted the ability to have detailed overviews of the whole site as often as we needed to plan work, communicate work plans, and validate and monitor work progress, says Jobard. To do that, we needed an aerial system that could be reliably deployed on demand, which didn t exist at the time. Jobard, however, had a possible homemade solution. With his penchant for remote-controlled aircraft, and his own collection of winged fliers, he decided to test the possibility of using a drone-type system for acquiring site imagery. He rigged an airplane with a consumer-grade digital camera, took some shots from an altitude of 150 meters (500 feet) and showed the photos to his boss. The proof of concept not only convinced Jobard s boss of the approach, it enabled Jobard to fly subsequent surveys to better determine what kind of aerial system they would need. In 2011, EDF issued a tender for an aerial system and began analyzing the proposed technology. With Somerset s frequent wind and rain, EDF would require a system that could sustain winds up to 40 kmh (25 mph) and operate in inclement weather. It also needed to be reliable, commercially operational, and come complete with customized, image processing software. After testing several European products, Jobard chose the Gatewing X100 UAS, an aerial mapping and surveying system that offers a An important part of the pre-flight checks: the pitot tube check.

Another successful automatic take-off! ground station, a tablet PC for pre-flight and in-flight operations, and a fixed-wing airplane with a 10 MP Ricoh GRD IV digital camera.

4 Another successful automatic take-off! ground station, a tablet PC for pre-flight and in-flight operations, and a fixed-wing airplane with a 10 MP Ricoh GRD IV digital camera. The X100 not only demonstrated a high tolerance to wind, it was commercially proven technology that offered us a one-stop shop package in both hardware, software and technical support, says Jobard. And although we originally planned to use the system to produce accurate as-found and as-built 2D maps and 3D models for monitoring work progress, we quickly realized the flexibility and informative substance of the system would enable us to develop a host of new applications to support and improve business operations at the site. No Pilot Required After receiving a license in May 2012 from the UK s Civil Aviation Authority (CAA) to fly the Gatewing X100 at Hinkley Point C, Jobard began acquiring aerial imagery over the 10,000-squaremeter construction zone, a relatively flat coastal area that rises between m (33-98 ft) above sea level. To date, Jobard has completed 55 flights and surveyed and mapped the entire site 20 times. For each flight, Jobard first checks the weather forecast to ensure wind The UAS has not only proven to be the most efficient and effective means to map the site, it has become a core data source for many business applications. conditions will be favorable ideally, less than 40 kmh and prepares the X100 for flight. He hand carries the 2-kilogram (4-lb) system to the center of the site, allowing him to survey any point in the area of interest, and assembles the launch catapult, which has a climb angle of 15 degrees. Jobard defines the flight path, including the geographic coordinates of the area to scan, and uploads the program into the X100 s autopilot system. He can then choose to preview the flight using a simulation feature to ensure the flight plan is correct and the system won t encounter obstacles. He sets the 100-cm (39-in)-wingspan airplane on the catapult and with one click, automatically launches it; once it reaches its cruising altitude of 150 m, Jobard watches the X100 fly the pre-defined, 45-minute flight and monitors the data from the onboard sensors (altitude, airspeed, voltage) on his ground control tablet PC via telemetry link. Once the flight is complete, the X100 then lands automatically, and the data is downloaded for processing. Though the UAS is capable of flying at altitudes up to 750 m (2460 ft), the CAA restricts flight heights in segregated areas to 150 m, and also requires operators to maintain visual line of sight, so

The Gatewing X100 ground station with a preloaded flight. The yellow lines are the flight path. Jobard often has another colleague with him to help observe flights.

5 sq miles) per flight, enabling Jobard to survey the entire Hinkley Point C site in two flights. Surveying the site by UAS is incredibly efficient, says Jobard.

5 The Gatewing X100 ground station with a preloaded flight. The yellow lines are the flight path. Jobard often has another colleague with him to help observe flights. At a cruising speed of 80 kmh (50 mph), and altitude of 150 m, the system can acquire up to 800 photos with a ground sample distance image resolution of 5.7 cm (2.2 in) and can cover 1.2 sq km (0.5 sq miles) per flight, enabling Jobard to survey the entire Hinkley Point C site in two flights. Surveying the site by UAS is incredibly efficient, says Jobard. In one afternoon, the X100 can collect millions of points on the ground in contrast to traditional land surveying that can acquire hundreds at most. From Flight to Sight Similar to the hands-off flying technique, processing the data with the system s customized Stretchout photogrammetric software is also largely automatic, says Jobard. To begin, Jobard uploads the camera imagery, flight recording data and coordinates of previously surveyed ground control points (GCPs) into the software for seamless integration. There are seven permanent markers around the site which were surveyed with RTK-GPS technology as reference points; and depending on need, Jobard uses manmade, cross-shaped markers that are surveyed for additional GCPs to increase accuracy. The software integrates the three data sources and Jobard then chooses the processing parameters. As the images are collected with a 75 percent overlap, Jobard can either click go and the software automatically identifies a few thousand common reference points The remediation area and the construction team s compound.

tiles for draping over orthomosaics. All of those outputs can then be exported in various formats for viewing or integration into other software such as GIS or Google Earth. Typically, a 20-cm (7.

6 Mission completed! It s time to have a cup of tea at the compound. between photos to produce a seamless, georeferenced orthomosaic, or he can choose more sophisticated functionality to produce point clouds, 3D models, orthomosaics draped over 3D models, or plane tiles for draping over orthomosaics. All of those outputs can then be exported in various formats for viewing or integration into other software such as GIS or Google Earth. Typically, a 20-cm (7.9-in) orthomosaic can be processed in less than two hours for a quick proof, but high-definition 2D maps and 3D models will require overnight processing. The 2D orthomosaics provide an excellent visual backdrop to practically any application and the incredible realism of the combined orthomosaics and 3D models gives us a very effective and flexible communication and monitoring tool, says Jobard. Extending the Wingspan Indeed, though the X100 was initially acquired as an aerial surveillance and mapping tool for the engineering department, its wingspan has quickly extended across a notable number of business divisions such as land surveying, security, facilities management, traffic management and communications. For my colleagues, the orthomosaics provide an accurate and different perspective of the site at any given time, enabling them to use them as a new operational tool. So now, the maps and models are forming the basis for anything that needs to be visualized for planning, design, measuring, monitoring or communicating. One of the first indications that the imagery would prove useful beyond mapping was during clean-up operations required at the site. Site orthomosaics supplied an accurate as-found map of scattered debris and rubbish that needed to be removed, but after work began, crews encountered asbestos, which required a different approach to clearing the contaminated soil. Jobard was able to process the weekly X100 flights into layered 3D models to calculate stock pile volumes to better monitor the soil excavation. The asbestos made it more difficult for crews to access the area, but the UAS was unaffected by it, which gave us the ability to not only continue to advance the work, it also gave us a remote measurement tool, says Jobard. We could use the point-cloud derived 3D models with orthomosaic overlays to measure the stock pile volumes of contaminated soil to ensure work was on target. Given the level of rainfall in the area, the X100 imagery aided engineers tasked with developing flood management strategies. The 2D maps effectively showed where water was pooling after heavy rains, enabling them to identify a suitable location to build a temporary reservoir. They could then monitor how quickly the reservoir filled with water to determine whether the structure was sound. Traffic management professionals used the imagery to help identify suitable locations for traffic signs and car parks; and a targeted X100 survey of a 10-km (6.2-mile) access road allowed them to determine whether that road, which has a few tight curves, would be sufficient for heavy equipment loads when construction begins later this year. The UAS has been an ideal surveying and mapping support tool for our preliminary site preparation work, says Jobard. And it will undoubtedly continue to provide frequent business intelligence and complement our traditional ground surveys as we move into earthworks and construction. With our nearly weekly flights, mapping with the X100 can be done on demand for 20 times less cost than conventional aerial photogrammetry, without sacrificing image quality. Given the success of the UAS for EDF, Jobard may want to consider finding a new hobby. To contact Rolophe Jobard, rodolphe.jobard@edf-energy.com Mary Jo Wagner is a Vancouver-based freelance writer with 20 years experience covering geospatial technology.

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