Preserving Romania’s Speleological Heritage with Point Cloud and GNSS Data

作者：乔治·达米安（George Damian），雷纳塔·巴拉达斯（Renata Barradas）

3D laser scanning provides a high-resolution, non-invasive documentation method to understand natural and cultural sites and manage its exposure to natural and man-made threats. Researchers in diverse fields are unlocking numerous applications using this technology, just like speleologists who are using laser scan data to study and measure caves with millimetre-level accuracy in a non-intrusive way. Point cloud data allows experts to extract cartographic information and calculate areas and volumes to study the evolution of topographic and bathymetric features in caves.

为了保存和了解罗马尼亚的杂种遗产，顶级地理，Leica Geosystems在罗马尼亚的经销商，Laser扫描了Meziad Cave，这是西方喀尔巴阡山脉的6,298米自然奇观。Meziad Cave是罗马尼亚旅游业的第一个洞穴，以其壮观的地下景观而闻名。该洞穴也是东南欧洲最大的蝙蝠殖民地之一和微观特有生物的所在地（其中一些被限制在Meziad Cave上）。

This high-resolution 3D documentation aimed to accurately capture the site’s complexity and to introduce positive conservation measures to maintain or restore the site before conducting any archaeological and palaeontological invasive research that can modify the original site. Moreover, Top Geocart created 3D models and other deliverables to enable its customer, Spelemat, to store, organise and retrieve information for further analysis. The data provided documents and records the in-situ state of this natural and cultural heritage.

A mission inside the cave

Together with specialists of Spelemat, Top Geocart designed the project and planned for this mission inside the earth. This group of specialists, who understand, respect and promote the use of techniques and geospatial data, collected field data without impacting the environment. Besides using non-intrusive/non-invasive techniques, the team also had to consider the right timing to enter the cave as weather and the cave's river flow were crucial factors to succeed in this mission.

Specialists from Top Geocart used best-in-class software and hardware, including:

• The Leica RTC360 3D laser scanner
• The Leica BLK360 imaging laser scanner
• Leica Viva GS16 GNSS智能天线
• Leica GS18 T RTK GNSS Rover
• Leica DISTO™ S910

For point cloud alignment, modelling and GNSS network the team relied on:

• Leica Infinity软件
• Leica Cyclone REGISTER 3603D激光扫描点云注册软件
• Leica Cyclone MODEL
• Leica Cyclone 3DR
• Leica GNSS蜘蛛软件

该团队通过GNSS Spider Software运行的罗马尼亚国家参考站网络（ROMPOS）的实时更正，通过GS16和GS18 T GNSS RTK ROVERS进行了搜寻，并通过GS16和GS18 T GNSS RTK Rovers进行了地理参考。需要智能链接校正，因为山坡和树木的山区环境阻碍了该区域，并且不时丢失了GSM/GPRS信号。GS16和GS18 T使用SmartLink服务的能力是涵盖这些空白的关键，并且始终具有精确的位置。为了提供最准确的职位，该团队还依靠两位RTK流浪者的Leica RTKPLUS技术，因为它通过选择最佳GNSS信号来智能适应不断变化的条件。

In the interior of the cave, the team moved through the river’s water with special clothes and accessories to safely transport the equipment. Inside of the waterproof containers and floating bags, the RTC360 and BLK360 drifted from location to location. Speed and precision are primordial while scanning with a water level above your chest in temperatures below 10 °C degrees.

该团队搭配RTC360搭配RTC360，捕获了洞穴和人工制品的较大部分，在不到两分钟的时间内创建了彩色的3D点云。在RTC360中，扫描速度最高为每秒200万点，高级HDR成像系统和无目标的现场注册，顶级Geocart以每小时750米的速度捕获了洞穴内部感兴趣的位置。

按下按钮，顶部的Geocart捕获了全彩色全景图像，覆盖在高准确点云上的洞穴狭窄部分，最小，最轻的成像激光扫描仪-BLK360。对于那些无法在三脚架上设置激光扫描仪的区域，使用Disto™910进行测量。

任务的可交付成果

Outside of the cave close to the entry, the team automatically and seamlessly transferred data from site to office using Leica Exchange, the exchange service provided by Leica Geosystems, reducing time in the inhospitable environment. Transferring the data easily between the field and the office with Leica Exchange allowed experts to perform a first check of the data onsite with Leica DISTO™ Transfer and Leica DISTO™ Plan App. UsingLeica Cyclone FIELD 360顶级地理automatically pre-registered and aligned scans at the cave's entrance.

Back in the office, point cloud data from the BLK360 and RTC360 was registered with Cyclone REGISTER 360. The GNSS data was checked and processed with Infinity software, in the GNSS project were imported the DISTO™ data, too. Together with Spelemat, Top Geocart created a unified point cloud, as Cyclone REGISTER 360 project, and exported in E57 and LGS formats to visualise it withJetstream观看器, a light-weight point cloud viewing tool. The E57 file was imported in Leica Cyclone 3DR to create meshes and compute digital terrain models (DTM) from point clouds.

专家们还创建了2D地形地图和3D DTM，其中包含来自GS16和GS18 T RTK Rovers的数据，以为访问者开发新的曲目和路径。从Disto™S910收集的数据中提取了带有3D点和图片的距离和CAD文件。

The data provided will support researchers, tourists and facility managers alike. It will guide feasibility studies for touristic plans and be used as marketing material to invite visitors to explore this natural wonder. Point cloud deliverables provide researchers with a digital twin of the cave where they can extract any profile and 3D measurement. At the same time, GNSS data helped to identify the areas and paths to create access for tourists and scientists.

“Leica Geosystems and Top Geocart provide complete software and hardware set for the entire workflow. The sensors have the capabilities to work in difficult environments and meet the highest standards in measurement excellence. The management and specialists fromSpelematadmitted they were capable of working more efficiently and in more challenging environments than ever before,”said Viorel Lascu, cave management expert at Spelemat.

成功的捕捉Meziad洞穴信服Spelematto invest in RTC360, BLK360, DISTO™ to keep exploring and understanding Romania’s natural wonders.