Creating an interactive 3D model of a cave in a world-famous glacier

Author:Tommaso Santagata，，，，Farouk Kadded

阿根廷的Perito Moreno冰川是世界上最重要的自然旅游景点之一。自19世纪以来，探险家和地质学家对其表面进行了研究，但是冰川中的腔体太危险了，无法步行探索。2017年，由意大利La Venta Esplorazioni Geografiche和法国Spélé'IceAssociations组织的一项研究项目旨在研究使用地面激光扫描（TLS）和无人驾驶汽车（无人驾驶汽车）的冰川边缘的入口。该项目的目的之一是记录将来可以使用的信息，以研究冰川冰融化的速度。收集到的三维扫描数据后来被用于创建一个交互式3D地图，该团队已公开可用。

Getting closer to the Perito Moreno glacier using 3D mapping

这Perito Moreno Glacier is located in Los Glaciares National Park in the Southern Patagonian Ice Field, the largest temperate ice mass in the Southern Hemisphere. It has an area of more than 250km² and extends 30 km from the Lago Argentino East towards the border with Chile West. Its relatively stable condition has made it one of the most famous tourist attractions in Argentina, drawing nearly one hundred thousand visitors each year.

关于冰川的洞穴知之甚少，因为它们太危险了，无法探索。从洞穴天花板上有很大一块冰块的不断掉落。作为Magpat项目的一部分（巴塔哥尼亚的微生物和冰川），La Venta Esplorazioni Geograficheand the FrenchSpélé’Iceorganised one of the first cave surveys of the area in 2017. The main objectives for the researchers were to investigate the micro-organisms living on the glacier and to map as much of the cave as possible. The only cavity that could be studied was an interesting contact cave excavated by a stream that directly feeds the glacier. A Leica Geosystems激光扫描解决方案was used to realise a 3D map of the first tens of metres inside the cave and the cave entrance.

Detail from a distance with the Leica ScanStation P40

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，远距离为270米。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 tabletcomputer, 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 fights were carried out with UAVs flying from 30 to 70m heights.

这Leica GS16- 用于摄影测量的地面控制点的自我学习GNSS智能天线 - 用于获取测量值，并测量沿冰川南北条带的速度和高程变化。它还与CS35平板电脑配对，以便可以直接在现场处理数据。

使用Leica Cyclone可视化3D数据

调查团队使用狮子旋风3D point cloud processing software to align the point clouds and create a 3D model. The model was then processed further with狮子旋风3DR创建项目可交付成果。Cyclone 3DR处理大多数行业标准的格式，因此团队能够将激光扫描数据与无人机拍摄的图像合并，以创建所需的模型。为了与团队以外的同事分享3D数据，Santagata使用了Leica Geosystems的免费Jetstream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.

Explore thePerito Moreno冰川中的接触洞穴的3D模型。
观看一些亮点冰川探险。

Organisations involved in the project: The Los Glaciares National Park, La Venta, Spélé’Ice, University of Milan-Bicocca, the Natural History Museum of Paris, Paris Diderot University, University of Florence, University of Bologna and Vigea – Virtual Geographic Agency.

激光扫描和GNSS调查是与法国Leica Geosystems的Farouk Kadded和Spélé’Ice Association合作进行的。