How to measure an island

In 2003, visionary Ben Kacyra foundedCyArk他的想法是创建一个免费的数字文化遗产和建筑档案，以保护它们免于自然或人类的破坏。在2001年在阿富汗拆除Bamiyan Buddhas的驱使下，Kacyra追求了这样的想法，以节省至少在以下几代人的3D蓝图中节省尽可能多的文化遗产。通过列卡·摩伊曼（Ken Mooyman），莉卡·摩曼斯（Leica Geosystems）执行副总裁，在西克（Cyark）的指示委员会上，该基金会在映射和调查方面拥有另一位专家和有远见的人。

With its knowledge and expertise in 3D laser-scanning to create high-resolution point clouds, CyArk took surveying and mapping of cultural heritage sites to another level. Within a short time, the foundation formed a worldwide network to add more than 130 projects to its archive, and launched in October 2013 its ambitiousCyark 500挑战to scan and digitally preserve 500 world heritage sites within a period of five years. One of the sites nominated by the500 Advisory Councilwas the tidal island St Michaels Mount in Cornwall, England.

The small island lying 366 metres off shore in the south-west of Great Britain, only reachable by boat or, at a low tide, via a causeway, is as well a postcard picture as a historical scene. First populated from circa 4,000 to 2,500 BC, it became a monastery during the 12^Thcentury and rose to the now known settlement and pilgrimage site during the 18th century. Endangered due to climate change and erosion, the500 Advisory Council建议的圣迈克尔斯山（St Michaels Mount）是一个文化遗产，应​​在数字上保存几代人。

Time savings with an UAV

To map this island,大西洋地理学andLeica GeosystemsUK配对调查岛和小别墅ge within three days using state-of -the-art technology and a trend-setting workflow involving an Unmanned Aerial Vehicle (UAV). With the technology and on-field knowledge ofLeica GeosystemsUK, the expertise in mapping and surveying from大西洋地理学, and the new approach in creating precise aerial using an UAV, a completely enhanced workflow evolved, changing the game in measuring and mapping large areas.

The choice to use the autonomous hexacopter to survey a cultural heritage site seemed like a long shot, but the versatile UAV had proven before to be the right pick for preserving structures. In 2014, Leica Geosystems UAVs created detailed 3D models of the library and stadium of the National Autonomous University of Mexico (UNAM).

2016年5月,10名船员苏尔veyors and pilots headed to the coast of Cornwall to start preserving the 0.23 sq. km (0.09sq. miles) of St Michaels Mount. The professionals needed high-end equipment to get ahead of this task. Besides the Leica GS16 GNSS to increase the accuracy of their GPS, the Leica MS60 MultiStation fulfilled its promise to create a 3D-grid with more than 1,000 points per second on a distance up to 300 meters during its work on the island. Moreover, the Leica ScanStation P40 worked with a range accuracy of 1.2 mm + 10 ppm and a 3D position accuracy of 3 mm at 50 meters to create fully textured 3D-Models of the cultural heritage site. With this great accuracy and precision both tools were the perfect addition to Leica Geosystems UAV solution, which measured the island aerial to create highly accurate orthofotos.

Streamlining the workflow

在岛上设置65个地面控制点，以捕获尽可能多的细节，工作人员开始为使用MS60多稳态以及GS16 GNSS进行测量准备。但是，面对崎terrain的地形，大胆的悬崖和大西洋潮的挑战，无人机的使用完善了专业人士的工作。将重型设备沿陡峭台阶载重的工程师非常耗时，这是一个主要的安全风险。在安全性和效率方面，使用Leica Geosystems Hexacopter获取详细的图像和无法访问的基础数据是一个相当大的优势。

With a flight altitude of 120 m above sea level, the UAV created precise data from the shorelines to the top of St Michaels Mount within 12 automated waypoint flights. By using the RTK/GNSS – module, the UAV flew with an accuracy of 1-3 cm calculating its precise position out of the data stream from 10 satellites. To get as many details as possible during the flight, the crew mounted the fully integrated Sony Alpha 7R to the hexacopters gimbal. A resolution of 7,360x4,192 pixels (36.4 megapixels) assured that every detail was captured and due to its full-frame Exmor CMOS-sensor an even higher quality was possible and less image noise was distributed. Recording the GPS-data per millisecond, every image taken can be precisely located. With the shutter speed set to 1/1000sec and the aperture to 3.2f, the mounted camera took at an ISO of 800 the pictures without any blur or distortion.

在拍摄高分辨率图片的时间和地点，具有列卡地理系统无人机内置的最详细的软件，可精确地标记为毫秒。这使您有优势将每个拍摄图像与后处理中最精确的GPS位置匹配。

通过使用无人机和最新设备，与没有空中支持的标准常规工作流程相比，调查的总时间减少了60％。

While the ground-team prepared the site for their measurements, the aerial-crew set the UAV up for its demanding challenge. With the in-house developed flight planning the crew programmed the parameters for the following flights so the hexacopter could gather aerial information in addition to the conventional results.

少捕获更多

After three days of flying, 12 automated flights to capture every detail of the island, and 4,120 taken georeferenced pictures, the crews came together to merge their data into the post processing software to create a digital high-resolution replica of St Mount Michael. The result was a 3D textured model of the island and its buildings, containing over 2.4 GB of high-res data, showing detailed insights of the cultural heritage. The combination of the captured data from all scanning devices in further data processing is as easy as 1-2-3. With a Ground Sampling Distance (GSD) of 3.2 cm and a relative accuracy in location of 1.2 cm in average, the UAV data was generated to point clouds and a Digital Elevation Model (DEM) with the support of a cloud-based hard- and software solutions. Thanks to software such as CapturingReality, Agisoft PhotoScan Pro, Autodesk ReCap and Pix4D, the combination of ground based scanning data and aerial images took only hours and not days and weeks.

通过整合Leica GeoSystems的飞行三脚架，可以扩展您在大型项目上工作的方式，使您能够在更少的时间内更精确地创建更多数据。但是，与轻松测量无法达到无法达到的区域并提高员工的安全性和准确性相比，效率是以前的两倍以上，这只是一种很好的享受。当您重新考虑映射和测量时，Leica Geosystems无人机解决方案是真正的交易。