3D cave mapping with handheld and terrestrial laser scanning

作者：Tommaso Santagata

In northern Italy, in the pre-Apennine area of Reggio Emilia is the "Tana della Mussina," a cave famous for archaeological artefacts found in excavations made in 1872 by Gaetano Chierici. As part of a research project with a local caving group - theGSPGC- the virtual Geographic agency Vigea recently 3D scanned the entrance part of this cave system using theLeica BLK2GO，手持式成像激光扫描仪。

移动扫描允许由托马索·桑塔加塔（Tommaso Santagata）从维亚亚（Vigea）领导的一支团队比以前的调查要绘制更多的洞穴，这要归功于设备的尺寸较小，重量较轻和快速扫描速度。该技术有可能使洞穴研究人员在具有挑战性的网站中捕获3D细节。

3D映射Tana Della Mussina

该项目由GSPGC洞穴组和FSRER洞穴协会。自1967年以来，GSPGC一直对意大利和国际地下世界进行探索，研究和研究。该小组发现并探索了许多洞穴，通常是相当大的发展和深度。他们与大多数意大利的Speleological（Cave研究）小组一起参加了许多探索性和研究合作。

The Tana della Mussina is part of the Cà Speranza-Mussina cave system, which itself is part of the Messinian gypsum (dated between 5.6 and 6 million years old). The gypsum developed with a series of discontinuous chalky outcrops characterised by the presence of several sinkholes, in many cases occluded by landslides of clay and marl, which drain the surface waters feeding karst systems. Karst is an area of land formed of soluble rocks such as limestone, dolomite, and gypsum. Gaetano Chierici’s excavation of the cave in 1872 found human remains from the Aeneolithic period (third millennium BC) and ceramic, flint and copper artefacts.

陆地激光扫描与洞穴系统中的移动映射

陆地激光扫描（TLS）仪器越来越多地用于3D地图自然和人工洞穴进行研究，提供了高度准确的细节。但是，并非总是可以创建完整的地图。地下环境本质上是具有挑战性的，通过狭窄和低通道可能难以进入，可能含有高水位，其寒冷温度使研究变得困难。

“There are sometimes limitations in the use of laser scanners which require tripods, or to be held in difficult positions to work safely, compromising the possibility of 3D scanning some complete cave environments. Handheld imaging laser scanners are newer instruments able to provide a 3D point cloud of the environment while walking. This kind of technology can be used for the almost complete capture of cave systems thanks to the possibility of moving much more comfortably and detecting in faster times,” Santagata explains.

测试Tana Della Mussina中的BLK2GO手持式成像扫描仪

As part of the GSPGC and FSRER project, Tana della Mussina was the object of 3D scanned surveys in 2019 and 2020. In the first survey, the cave was 3D scanned using aLeica Scanstation P40survey-grade, high-definition 3D laser scanning solution and the BLK2GO, a handheld, wireless, and lightweight imaging laser scanner. The data acquired was processed to create topographic maps. In June 2020, the BLK2GO scanner was tested with the objective to 3D scan the same part of the cave already mapped in the previous campaign.

Santagata explains the mapping process, “Integrated with an Inertial Measurement Unit (IMU), the BLK2GO allowed us to 3D map and acquire RGB data information to obtain coloured 3D point clouds. The BLK2GO recreates spaces in 3D as you move. Paired with an iPhone and using Leica Geosystems’ dedicated application, it allowed us to view a preview of the results in real time and control the instrument, with the possibility of acquiring photographs and adding GeoTags to be viewed in the exported point clouds.”

Future of cave scanning – combining instruments for freedom and high definition

Santagata reflects on the success of the project and the potential for mobile mapping in cave scenarios, “New innovations in 3D laser scanning technology can bring progress in speleology, especially through the use of portable mapping systems. Handheld mobile mapping tools such as the BLK2GO are able to get different details from traditional laser scanner systems (which can guarantee much more precision and higher definition) allowing us to detect in 3D in underground environments with more freedom.”

至关重要的是，通过集成不同的系统，可以使用陆地激光扫描仪在感兴趣的领域获得更大的细节，并在短时间内与手持式系统快速对环境进行快速的全球映射，这是理想的结果。”

探索3D中的项目：
在洞穴中进行测试
Data Elaboration Inside来自Valerio Brunelli
数据详细说明来自Valerio Brunelli

Key people involved in the project: Tommaso Santagata (Vigea - Virtual Geographic Agency), Valerio Brunelli (Leica Geosystems Italy) and Stefano Bergianti (Gruppo Speleologico Paletnologico Gaetano Chierici di Reggio Emilia).

Further reading:
DE WAELE, J., FABBRI, S., SANTAGATA, T., CHIARINI, V., COLUMBU, A., PISANI, L.(2018)Geomorphological and speleogenetical observations using terrestrial laser scanning and 3D photogrammetry in a gypsum cave (Emilia Romagna, N. Italy). Geomorphology,319, 47-61.