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mine design continued mum efficiency. The mine plan will change dynamically, taking advantage of the 3-D mine���s comprehensive data-sharing capabilities to ensure everyone is looking at the most up-to-date version. This scenario is very much within the grasp of today���s mine operators, said Maier, although maximum benefit will be derived at sites that have been developed from the start with peer-to-peer 3-D capabilities and maximum connectivity as basic operating strategies. An Eye in the Sky An alternative to terrestrial surveying and traditional aerophotogrammetry involves the use of unmanned aerial systems (UAS)��� small, remote-controlled airframes that can be programmed to fly in precise patterns over medium-sized areas, collecting raw digital images of the terrain which can then be processed into high-quality orthophotos and digital terrain models (DTMs). The key technological advances driving the rising popularity of these systems include greater miniaturization of components, flight automation and better integration with image-processing software. Although UAS are not appropriate as a replacement for all applications that typically would use conventional imaging or surveying methods, they can provide highly useful data in areas that may previously have been accessible only at higher cost and involving longer project-planning cycles. In suitable applications, UASbased imagery can provide significant time savings over conventional methods, along with worker and asset safety gained by eliminating human involvement in the actual flight. Although extremely lightweight UAS are largely restricted to flights in good weather conditions, the slightly larger (2+ kg) airframes typically used in mining applications can fly in almost any type of weather and still provide 2���3 cm ground sample resolution accuracy, according to experts. To gain a foothold in this sector, Trimble acquired UAS vendor Gatewing of Gent, Belgium, in April 2012. Gatewing���s products include the X100 UAS and Stretchout desktop software for digital image processing and analysis. The ultralight X100 consists of an airframe; an integrated GPS, inertial system and radio packaged as an ���eBox���; a 10-megapixel camera; and battery. Using a tablet computer, users can define a flight plan that is automated from launch to landing. Terrain features are recorded during parallel flight paths by consecutive, overlapping camera shots. A ground control station (GCS) is used to monitor the mission and allows an on-site image quality check. In addition, the GCS provides the operator with the option to intervene and abort the flight if needed. The image set consists of a number of digital images that are tagged with GPS coordinates. The Stretchout desktop software automates processing of raw images taken in flight to deliver georeferenced orthophotos and accurate DSM. As an alternative to the desktop software, users can upload images to Gatewing���s cloud solution, which automatically processes the images based on the users��� requirements. Within hours, users can download their orthophotos and DTMs from the cloud server. The Gatewing UAS comes in a large suitcase-sized kit which includes the 2-kg (4.4lb), 100-cm-wingspan airframes and its eBox, an extra body, launcher, ground control station, modem, calibrated digital camera, lithium polymer batteries and charger, tracker tool, and spare parts and accessories, along with the Stretchout software. Mark Bartlett, director of open-pit mining innovation at Newmont Mining Corp., told a Dimensions conference audience that he began screening several types of UAS about a year ago, looking for an answer to the question ���Is this an application we can use in mining?��� The Gatewing product, he explained, appeared capable of filling a The Gatewing X100 is one of several unmanned aerial system (UAS) products suitable for conducting low-risk digital imagery of ground surface features. 36 www.coalage.com niche in the company���s field and mine-site surveying activities, and offered some unique capabilities when compared with conventional methods. In particular, Bartlett noted, Newmont was interested in using a UAS for assessing and mapping possible drill roads and pads, evaluating facility area-footprint characteristics, and recording prior-disturbance details on land tracts. In a recent field test, Bartlett���s crew used the Gatewing system to provide digital imagery of a rugged jungle area near one of Newmont���s African operations. Over the course of 36 flights���which required three airframe replacements due to damage from landings���the crew gained experience and insight into the benefits and drawbacks of UAS operations. These include: ��� Careful attention to takeoff and landing sites���Because the UAS requires its own ground-based launcher, takeoff sites need to be reasonably unobstructed; and, as landings are basically controlled crashes, certain kinds of ground surfaces and vegetation (short to medium grass, for example) are better than others (bare dirt). In addition, selecting different takeoff and landing sites may confuse the system and result in crashes. ��� Awareness of atmospheric conditions and ground elevation changes��� Although a UAS can fly below cloud cover that would prevent a conventional manned photogrammetry flight, because of its light weight it is very sensitive to air density, which can affect takeoff and laning, performance at higher elevations; and thermal currents that can affect its flight path. And, because the number of photos the system will take depends on its distance from the ground, significant changes in surface elevation along the flight path can cause it to take fewer photos than expected in some cases, resulting in coverage gaps. ��� Data collection and processing���UAS flights generate large files, so some forethought should be given to where these files will be stored and how they will be processed. Because the processing is highly graphics-intensive, Bartlett suggested using a powerful computer with high-end graphics capabilities���possibly, a gaming computer. And, although the standard UAS kit may include basic processing software, users may want to purchase more sophisticated software solutions to save time and extract complete value from the data. Industry observers suggest that UAS solutions will compete more directly with February 2013