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 Challengeto 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.

位于英国西南部距离海岸366米处的小岛，只能乘船或在潮汐低潮时到达堤道，也是明信片的照片，也是历史上的照片。首先从公元前4,000至2,500年居住，在12期间成为修道院^th在18世纪，Century and升至现在已知的定居点和朝圣地。由于气候变化和侵蚀而濒临灭绝，500 Advisory Council建议的圣迈克尔山（St Michaels Mount）是一个文化遗产，应​​在数字上保存几代人。

用无人机节省时间

To map this island,大西洋地理学和Leica Geosystems UKpaired up to survey the island and the small village 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 Geosystems UK, 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).

In May 2016, a crew of 10 surveyors 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.

简化workflow

Setting up 65 ground control points around the island to capture as many details as possible, the crew started to prepare the site for measuring with the MS60 MultiStation as well as the GS16 GNSS. But being challenged by rough terrain, bold cliffs and the Atlantic surge, the use of an UAV refined the work of the professionals. Engineers carrying heavy equipment down steep steps is a major safety risk as it is very time consuming. Using the Leica Geosystems hexacopter to get detailed imagery and data of inaccessible ground is a considerably advantage when it comes to safety and efficiency.

无人机在12个自动化的航天飞机中，飞行高度高于海平面120 m，从海岸线到St Michaels安装座的顶部创建了精确的数据。通过使用RTK/GNSS - 模块，无人机以1-3 cm的精度飞行，从10颗卫星中计算出其精确位置。为了在飞行过程中获取尽可能多的细节，机组人员将完全集成的Sony Alpha 7r安装到了己型甲板上。一个分辨率为7,360x4,192像素（36.4兆像素），确保捕获每个细节，并且由于其全帧Exmor CMOS传感器，可以更高的质量，并且分布较少的图像噪声。每毫秒记录GPS数据，拍摄的每个图像都可以精确地位于位置。将快门速度设置为1/1000秒，孔径为3.2F，安装的相机以800的ISO拍摄，而没有任何模糊或失真。

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。

By using an UAV and latest equipment, the overall time for surveying was reduced by 60 per cent compared with the standard conventional workflow without aerial support.

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.

Capturing more with less

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.

Expanding your ways to work on large-scale projects by integrating the flying tripod from Leica Geosystems gives you the ability to create more data, more precisely in less time. But being more than twice as efficient as before is just a nice treat compared to measuring unreachable areas easily and increasing the safety and accuracy of your staff. Leica Geosystems UAV solution is the real deal when you rethink mapping and surveying.