创建世界上最大的火山洞的3D地图，以帮助未来的太空任务

Despite being hundreds of thousands of kilometres apart, the island of Lanzarote and the Moon share remarkable similarities. The Spanish island, belonging to the Canary archipelago in the Atlantic, is home to the world’s largest volcanic cave and exceptional scenery that resembles the lunar landscape. So much in fact that the island has been chosen as a location for astronaut training ahead of space missions. More recently, Lanzarote’s Corona lava tube has helped prepare teams at the European Space Agency to explore and study caves of similar characteristics observed on the Moon and on planets like Mars.

As a result of the latest advancements and innovation in geospatial technology, several field surveys were conducted in 2017 led by Tommaso Santagata from the Virtual Geographic Agency维亚，部署3D陆地激光扫描（TLS）和Mobile Mapping solutions，导致地球上最大的熔岩管的第一个3D复制品。

Exploring the depths of the Corona lava tube

电晕熔岩管位于兰萨罗特（Lanzarote）的北部，延伸超过8.5公里，由干燥和淹没的通道组成，其中一些部分宽25米。尽管最初的探索和初始映射始于七十年代，但直到第一个地形调查进行了六十年代初，其真正的扩展才是未知的。由地方政府Cabildo de Lanzarote委托的最新，最雄心勃勃的3D扫描项目也实施了最新的移动地图技术，该技术是欧洲航天局培训课程Pangaea-X的一部分。这项培训使他们能够测试将在未来太空任务中使用的新工具和技术。

In order to successfully execute this project, various field surveys were completed over the course of a year deploying a variety of Leica Geosystems solutions, including theLeica HDS7000,Leica Scanstation P40andLeica BLK360激光扫描仪以及Leica Pegasus:Backpack移动映射解决方案。结果是地球上熔岩管的最大3D复制品，绘制了5.7公里的洞穴通道。

Capturing every detail with the latest laser scanning technology

Three individual surveys and over 440 scans were completed to map the lava tube system, composed of different sections connected to each other through external collapses. These collapses were used to geo-reference the laser scanning surveys performed inside the cave on the external surface. This was made possible with Global Navigation Satellite System (GNSS) measurements, Light Detection and Ranging (LiDAR) data from the Spanish Geological Service, and through photogrammetry data obtained with unmanned aerial vehicle (UAV) flights along the cave path.

更具体地说，使用HDS7000绘制了800米的上述海平面通道，并使用扫描仪P40估计五公里。此外，在Pangaea-X探险期间，还部署了BLK360成像激光扫描仪以扫描约300米的高层。

Increased accuracy and mobility with the Leica Pegasus:Backpack

To generate an even more detailed 3D map, a survey was performed using the Pegasus:Backpack mobile mapping solution. Designed to capture 3D data in overground and underground environments, with images and point clouds collected by five cameras and two LiDAR profilers. Its lightweight and ergonomic structure allowed teams to comfortably navigate the difficult terrain and to instantly visualise the data on a handheld tablet computer.

“由于熔岩管系统的复杂和地下性质，Pegasus：Backpack被部署以获取融合的SLAM数据 - 在带有GNSS数据的户外环境中开始和结束，但在很大程度上探索了没有卫星的洞穴，”Co-Founder of Virtual Geographic Agency Vigea 3D and an expert on Lanzarote’s volcanic cave system. As the lengthiest part of the mission was carried out without any GNSS information, the second phase of the data processing was to reinforce the calculation of the path recorded using a SLAM algorithm and the information obtained by the LiDAR mounted on the Pegasus:Backpack.

Processing the data and creating the final 3D map

“Having gathered large amounts of data — 400 GB corresponding to the raw laser scanning data alone — theLeica Cyclone3D point cloud processing office software was then deployed to align the scans and process a unified point cloud of the cave,” says Santagata. “Once the 3D map was available in a single point cloud, several outputs were generated as topographic maps with plans and sections of the lava tube.” In addition, the data was subsequently used to produce comparisons with other lava tubes on earth, with the objective of studying similar features on the Moon and Mars — this operation was performed using theAutodesk AutoCAD2017 software.

除了科学purposes and training for future space missions, the data was also used to produce multimedia and interactive contents like video animations, virtual reality and desktop applications showing the wider public the lesser known parts of the Corona lava tube system. Only limited sections are open to the public at Cueva de Los Verdes and Jameos del Agua. Furthermore, the results of this project were presented during an event on the management of touristic caves organised by the Cabildo de Lanzarote in 2019, where a virtual reality stand was installed to show the cave to the public.

Latest expedition update: Supporting the search for “stone-eating” bacteria

In spring 2021, Santagata returned to Lanzarote to support a microbiology research project. The Tubolan project, led by Ana Miller, geomicrobiologist at the Institute of Natural Resources and Agrobiology of Seville (CSIC), was set up to study the microbial organisms living in the Lanzarote lava tube systems. The team’s findings will help those searching for life on the Moon and Mars, which also have lava systems. Although the conditions are different to those on earth, the Martian and lunar cave systems could theoretically also support chemolithoautotrophic microorganisms that survive and grow by using and transforming minerals. In the framework of the Tubolan project, Santagata used a Leica BLK360 to make scans and 360 degree videos – contributing to the study of caves’ formation and uncovering more of the caves’ geography than ever before. The amazing video footage taken can be watched onVIGEA’s YouTube channel。

Further reading:
SAURO F., POZZOBON R., SANTAGATA T., TOMASI I., TONELLO M., MARTÍNEZ-FRÍAS J., SMETS L.M., GÓMEZ G.D., MASSIRONI M. (2019)兰萨罗特的火山洞：一种自然实验室，用于了解火山孔隙遗传学过程和行星洞穴。在Lanzarote和Chinijo群岛地质公园中：从地球到太空（第125-142页）。施普林格，康。

SAURO F, POZZOBON R。DE BERNARDINI MASSIRONI MS P., SANTAGATA T., DE WAELE J. (2020)Lava tubes on Earth, Moon and Mars: a review on their size and morphology revealed by comparative planetology。地球科学评论103288。