在举世闻名的冰川中创建洞穴的交互式3D模型

作者：Tommaso Santagata,Farouk Kadded

The Perito Moreno glacier in Argentina is one of the most important natural tourist attractions in the world. Its surface has been studied by explorers and geologists since the 19th century, but cavities in the glacier are too dangerous to explore on foot. In 2017 a research project organised by the Italian La Venta Esplorazioni Geografiche and the French Spélé’Ice associations set out to study the entrance to a cave at the edge of the glacier using Terrestrial Laser Scanning (TLS) and unmanned aerial vehicles (UAVs). One of the aims of the project was to record information that could be used in the future to study how fast glacial ice is melting. The three-dimensional scanning data collected was later used to create an interactive 3D map, which the team has made publicly available.

Getting closer to the Perito Moreno glacier using 3D mapping

Perito Moreno冰川位于南部半球最大的温带冰块的南部巴塔哥尼亚冰场的Los Glaciares国家公园。它的面积超过250公里，从拉哥阿根廷东部延伸到与智利西部边界30公里。它相对稳定的状况使其成为阿根廷最著名的旅游景点之一，每年吸引近十万名游客。

Little is known about the caves of the glacier because they are too dangerous to explore; there is a constant fall of large chunks of ice from the cave ceilings. As part of the MaGPat Project (Microorganisms and Glaciers in Patagonia),La Venta Esplorazioni Geograficheand the FrenchSpélé’ies2017年，有组织的该地区的最初洞穴调查之一。研究人员的主要目标是研究生活在冰川上的微生物，并尽可能多地绘制洞穴。唯一可以研究的腔是一个有趣的接触洞穴，该洞穴被直接馈入冰川的流挖出。Leica Geosystems激光扫描解决方案被用来实现洞穴和洞穴入口内第一米的3D图。

与Leica ScanStation P40远处的细节

3D laser scanning technology has proven transformational for geographic surveys, explains Tommaso Santagata from La Venta, “These techniques are increasingly used in geological studies, such as in caves or for the calculation of ice surfaces and changes in ice volumes. 3D laser scanning technologies can acquire millions of points represented by 3D coordinates, at very high spatial densities on complex multi-faceted surfaces within minutes. The dense point clouds contain a huge amount of data that can be used for representation and analysis.”

在Perito Moreno研究中，团队使用了Leica Scanstation P40，可以捕获高质量的3D数据和高动力范围（HDR）成像，在270米长的范围内。调查级3D激光扫描仪位于安全距离处，以获取冰川表面和洞穴入口的数据。它是使用一个Leica CS35平板电脑computer, which the team also used to check partially processed data while they were still in the field. In this way they were able to make sure the survey was progressing as planned, while still able to make changes. A dedicated camera integrated into the scanner was used to produce coloured point clouds and take 360° panoramic images.

Santagata explains the process, “About eight laser scans were performed to acquire the necessary data. These operations took about two hours and were realised in the late afternoon in order to have the area not directly illuminated by the sun. Laser scans were produced with resolutions of 6mm and 3mm (which represent the distance of each single point measured at 10m from the laser scanner) and acquiring photographs with the internal camera of the instrument.” In addition, photogrammetry flights were carried out with UAVs flying from 30 to 70m heights.

TheLeica GS16- a self-learning GNSS smart antenna - was used to acquire measurements, both for ground control points for the photogrammetry survey and to measure velocity and elevation changes along a north-south strip of the glacier. It was also paired with the CS35 tablet computer so that data could be processed directly in the field.

使用Leica Cyclone可视化3D数据

调查团队使用狮子旋风3D点云处理软件可以对齐点云并创建3D模型。然后将模型进一步处理狮子旋风3DRto create the project deliverables. Cyclone 3DR handles most industry-standard formats so the team was able to merge the laser scanning data with images taken by the UAV to create the model they required. To share the 3D data with colleagues outside the team, Santagata used Leica Geosystems’ freeJetstream观看器，这使任何人（甚至没有3D建模经验的人）都可以轻松查看和操纵点云。

Sharing information with the scientific community and beyond

Santagata explains that the detailed 3D models of the glacier give researchers an accurate record from which to measure changes in the ice: “The possibility to have such technologies in the right moment and right place allowed us to use them to obtain data that can be used in the future to compare the evolution of this part of the glacier.”

Following the trip, 360° photographs from the 3D models and a 3D interactive model were produced to show the results to anyone with an interest in the area. At the International Speleological Meeting in Italy in 2019 it could be viewed using virtual reality glasses, and it now lives online.

探索3D model of a contact cave in the Perito Moreno glacier.
Watch some of the highlights from theglacier expedition.

参与该项目的组织：Los Glaciarres国家公园，La Venta，Spélé’ies，Milan-Bicocca大学，巴黎自然历史博物馆，巴黎狄德罗大学，佛罗伦萨大学，博洛尼亚大学，维亚纳大学和维亚维亚大学 - 虚拟地理局。

Laser scanning and GNSS surveys were carried out in collaboration with Farouk Kadded from Leica Geosystems France and member of Spélé’Ice association.