troubl- Using laser scanning to capture the new Höllentalklamm (Hell’s Gorge) bridge in the German Alps

作者：托马斯·肖克（Thomas Schock）

Hollentalklamm -英文“地狱峡谷”——near Garmisch-Partenkirchen is a unique natural spectacle 1,000m high in the German Alps. It’s part of the hiking route to the Zugspitze peak, a connection only made possible due to a historic bridge across the gorge, built in 1905. Due to its age and deterioration, the bridge and several footbridges had to be replaced in 2020. The local members of the德国高山协会（DAV）为250,000-Euro项目筹集了资金，并找到了两个关键的公司赞助商 - 运输基础设施专家ZÜBLIN / STRABAGandThyssen-Krupp。

Strabag是Leica Geosystems的合作伙伴，使用激光扫描解决方案以数字方式捕获新的桥梁。该调查表明，即使在这种“地狱”环境中，扫描仪的表现能力也是如此。创建的数字计划将用于将来维护。

Replacing an historic and much-loved bridge

The construction of the first bridge over the gorge took 600 working days to complete, from 1902 to 1905. An impressive feat of engineering, it was completed almost by hand, without electricity or modern machinery. Today, the build materials could be delivered by helicopter at least to the Höllental entrance at 1045m. From there the team, made up of ZÜBLIN / STRABAG engineers, local construction company Florian Dörfler and DAV volunteers, needed to drag the components to the construction site 200m away. To transport the bridge, which weighed over four tonnes, into the narrow gorge, it was divided into some 600 individual parts. The custom bridge and walkway elements were prefabricated by ZÜBLIN’s Structural Steelwork subdivision in Hosena, Brandenburg.

尽管几乎是完美的初步计划，但一些障碍是不可避免的。事实证明，卸下桥支架的岩石被锚定的岩石要比预期的要困难得多。尽管如此，构建只花了四个星期。Züblin网站经理PhilippSchön总结说：“在HöllentalkLamm非常特别的背景下，准备工作，最后是该赞助项目的执行真是太棒了。来自各个项目参与者的团队就像一台油腻的机器一样，共同努力。”

便携式，健壮且高度准确的激光扫描解决方案

Once the bridge was replaced, Philipp Mielke, Technical Group Manager at STRABAG with Johannes Zettel, Marketing and Thomas Schock from Leica Geosystems used both theLeica RTC360andBLK2GOto capture a digital twin of the new arch bridge using laser scanning.

The RTC360 provides a clean and highly accurate point cloud while being highly portable. In fact, together with its carbon tripod, it fitted in a backpack and was hiked up to the gorge from the car park. It is also robust - IP54 rated so able to cope with splashes of water - ideal for the wet mountain environment.

BLK2GO是一种手持式成像激光扫描仪，在移动时会重新创建3D空间。操作员-Schock-能够一只手携带并在行走时进行扫描，从而轻松保持平衡并意识到湿滑的地形上的危险。用于处理数据的软件是Leica Cyclone REGISTER 360，，，，Leica CloudWorx，，，，Leica TruView EnterpriseandLeica Cyclone 3DR。

从捕获桥梁到数据共享

Using the RTC360, Schock carried out scans across five viewpoints: three scans were taken on the bridge, two on either side from 50m away, looking towards it. This created a picture of both the bridge and the rocks of the narrow gorge on all sides. HDR images were taken with the scanner at five exposure stops to allow for an RGB inspection for dark areas (tunnels) and bright areas (those in full high-altitude sunlight). Speaking about the unusual conditions, Schock says, “Surefootedness and a head for heights are required in the Höllentalklamm! But the ascent was quickly mastered with the lightweight RTC360.”

Using the BLK2GO handheld imaging laser scanner, Schock completed several walks taking around 10 minutes, covering 150 - 200m of terrain on each side of the bridge. This was done with enough overlap in the connection areas to allow for the linking of successive trajectories with the Cloud2Cloud algorithm from Cyclone REGISTER 360.

扫描后，使用Cyclone寄存器360用于导入，准备和优化数据，以提供在其他Leica Geosystems和第三方应用程序中使用的LGS数据集。Truview Enterprise用于可视化，这是一种与项目中的其他人共享点云数据的快速简便方法，Leica Cyclone 3DR将用于隔离峡谷和隧道的数据。

Impressive results even in “cramped and constrained conditions”

The Höllentalklamm bridge project was an ideal opportunity to put the latestLeica Geosystems3D laser scanning equipment进行测试。尽管该位置难以访问，而且天气状况具有挑战性，但激光扫描仪与海平面一样易于使用。

肖克说：“两种扫描仪都按预期进行，结果超出了预期。”Strabag的Philipp Mielke同意：“使用RTC360的桥梁扫描结果非常好。即使在这些狭窄且受约束的条件下，我们也没有问题扫描桥梁。”该公司已经在其他隧道和建筑项目中使用了RTC360，目前正在进行或计划进行BLK2GO的进一步测试。