UAV-based mapping of the Porgera mine

Papua New Guinea, one of the most rural and unexplored places on the planet, challenges surveyors with its dense rainforest, swamps, steep valleys and mountains up to 4,500 meters to find new ways to create accurate measurements. To defy these difficulties, the experts are forced to search for new innovative solutions to obtain precise results and found their perfect match in the use of an Unmanned Aerial Vehicle (UAV).

When Benchmark Survey & Design, experts specialised in topographic site surveying from North Queensland, Australia, were contracted by the Porgera Mine Survey Team to map spill grounds around the secluded mine located at the head of the Porgera Valley in highlands at an altitude of 2,200 to 2,700 m, they needed to find a new method of surveying. As the captured data would be used for environmental monitoring of the dump sites generated by the mine, accuracy was of the utmost importance.

Mapping dangerous terrain with an UAV

在山体滑坡和地震很常见的区域，只有五天可供映射，基准调查和设计确定了空中调查是收集所需数据的最安全，最有效的方法。由于该公司在使用Leica Geosystems UAV方面需要更多的经验，因此它转向了一家在地理信息系统（GIS）超过20年的澳大利亚公司的空间技术，以提供无人机飞行员。在过去两年中，Flying Leica Geosystems无人机并在各种环境中收集数据，空间技术是挑战的。

With two sites to capture around the mine, Anjolek at 380 Hectares and Anawe at 250 ha, the pilot, Anton van Wyk, had to carefully plan his route in the flight planning software. Facing several challenges, like steep and unattainable terrain only accessible by helicopter, use of the helicopter only available one out of the five days to map, and extreme weather with heavy fog in the mornings and continuous rainfalls in the afternoon, reduced the time bucket to only a few hours each day to survey. Anton’s precise plan rested upon the durability and dependability of Leica Geosystems UAV solution.

“Leica Geosystems UAV provided better results than what Porgera Mine Survey Team expected, even in such rough terrain,” said Wayne Storey from Benchmark Survey & Design. “Though the mine survey team had someone prior fly this mission, the team didn’t receive the expert mapping and processing of the data the UAV delivered with its more advanced sensors.”

With 32 total flights at about 10 minutes each, Spatial Technologies collected 9,100 orthophotos at a 5 cm ground sampling distance. While Benchmark Survey & Design only need sub-metre accuracy for the project, Spatial Technologies was actually able to supply 10-20 cm accuracy with strategically placed controls in conjunction with the RTK on the UAV. The entire project was processed in about 96 hours to provide visual documentation of volume changes in the spill grounds.

More than just volumes

Combining the orthophotos from Leica Geosystems UAV with older data and point clouds of the site created by laser scanning technology, engineers and environmentalists on the project were enabled to go beyond just volume calculations. Together with the many forms of data collected, they can now see visible proof of vegetation changes and conduct slope analyses.

随着危险的地形唤起了测量师的危险条件，以前对测量值进行了很少的测量。借助更安全，更快的无人机调查，矿山调查团队现在可以更定期地监视，以更快地管理问题并在成为主要问题之前纠正问题。

“Aerial surveys with an UAV can not only be done quicker than with traditional methods, but with the advanced sensors it can carry, we can gain the same if not better accuracy, as well, “said van Wyk. “Since surveyors don’t have to enter risky areas, too, to set up instruments, the UAV also makes our jobs safer.”

When terrain creates obstacles on the ground, UAVs are able to overcome from above. Opening access to more and more areas, Leica Geosystems UAV solution is creating new opportunities across the globe.