结合了快速形态调查的测深量和激光雷达数据

作者：Sam Pfeifle

当它到达国家线分开洗涤ton from Idaho, the Snake River forks, one tine flowing to the south as the Snake along the border, the other heading due east as the beginning of the Clearwater. Anyone traveling east on a boat would quickly encounter the Clearwater Memorial Bridge, a roughly 228-metre-long bridge dedicated to veterans of WWII.

这座桥,在1951年的春天,是德gnated ‘functionally obsolete’ by the federal government more than a decade ago, largely because of the roads that feed it, which are no longer suited to the traffic the bridge handles daily.

In March of 2019, almost 70 years after its construction began, the Idaho Department of Transportation entrusted a pair of engineering companies with creating a full topographic survey of the bridge and surrounding area as part of a multiyear project to replace it and surrounding roadways, ensuring safe and efficient transportation for generations to come.

这项工作首先Horrocks Engineers，在整个美国西部设有15个办事处，其中包括爱达荷州的三个办事处。Horrocks的校长和调查经理Lonnie Olson说，收集桥梁和周围道路的调查数据是其移动地图部门的标准工作，但该项目还要求为河底和桥梁子结构提供测深数据。

“They wanted a look at the scour around the bridge pilings,” Olson said. “One of the avenues they’re looking at is to keep the substructure and much of the bridge itself.”

他知道，在移动映射云数据中添加多层声纳数据将使最终的TOPO一致，细粒度，准确的数据从河流底部开始，但存在一个问题：Horrocks没有一个多层声纳单元。

奥尔森说：“在犹他州，我们没有任何大河流，大多数湖泊不需要太多的测深数据。”“我们通常只是做单束声纳，这不是我们在这里想要的。”

Luckily,Spicer组has a multibeam unit for just this kind of bridge-scour analysis and hydraulic modelling. Even better, Spicer’s sonar vessel is also fitted with aLeica Pegasus：两个移动传感器平台用于其高于水线的移动映射，同一移动扫描平台Horrocks在其道路映射的前18个月投资了。

Olson decided to reach out to Spicer project surveyor Nathan Shepherd and combine forces on the job—the first time he’d ever subcontracted out to another surveying team.

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Done in a Day

Horrocks would drive the bridge and surrounding roadways. Spicer would drive the river to get everything below waterline, the riverbanks, and the underside of the bridge. Then they’d stitch the data together, extracting the planometrics to create a surface model and topographic survey.

由于Pegasus是一个能够从多个来源摄入数据的传感器平台，因此可以将多光束和LIDAR信息集成到单点云中。

牧羊人说：“飞马座的山被螺栓固定在船上。

Shepherd解释说，虽然Pegasus的LiDar单元只需在桥下和河岸沿着河岸的一个来回抓住一切，但Multibeam更像是割草。该团队在多束中需要40或50次通过，以获取河流的底部以及所有清除率高和液压研究所需的数据。

尽管如此，一切都在一天之内完成。

总而言之，大约花了三天的时间来建立工作的完整控制网络，然后在现场准备和进行实际扫描四天，总共在现场进行了7天 - 与传统方法相比，大量节省了时间。

“Ten years ago,” said Olson, “you would have had to cross-section every 50 feet with a robotic total station and shoot in some key points of the structure, and you’d have to spend probably three to four weeks onsite doing control and collection.”

至于水下工作，“您可能每250英尺一次横截面，也许是单束声纳的总测量，然后是一个模型，” Shepherd说。“而且他们将无法获得搜查。没有办法知道这一点。他们本来不得不将潜水员送到视觉上看它。

因此，大约有三分之一的时间，” Shepherd总结说，“而且我不知道数据多了几百倍。”

Even better? “When I pulled it all together,” said Olson, “our clouds lined up with a less-than-centimetre accuracy between Spicer’s and our upper and lower data. You would never find that kind of accuracy any other way. You could achieve it, but the cost would be exponential.”

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移动映射的后台效果

您可能已经听过恐怖故事：“移动映射创建了很多数据，以至于无法管理！”“当您要做的就是驾驶扫描仪时，谁需要一个调查团队？”

Of course, it’s true that moving into mobile mapping is going to require back-office adjustments, but they should be relatively manageable if you prepare for them and offer training to your workforce.

Horrocks工程师已经进行了激光扫描大约八年了，但大约18个月前就购买了Mobile Scanning，购买了Pegasus：Hexagon一部分Leica Geosystems的两个平台。bob体育报道Horrocks的校长和调查经理Lonnie Olson说，这绝对影响了他的劳动力。

“Some of our field crews transitioned indoors,” he said. “And I have a team of former high-ranging CAD techs that we’ve trained to do survey work. We’ve been able to do most of the post-processing work in-house.”

他们还招募了本地地理学计划的近期毕业生，并在他们加入移动点云数据后立即开始培训。

奥尔森说：“现在我们有一个由五个人组成的团队，除了每天整天从点云中提取数据外什么都不做。”

Leica Geosystems’ Jason Ellis said Horrocks’ experience is typical, and the movement of field staff into the back office should be seen as a smart move and not a conciliation.

“The continuity from the field to the office is always a challenge,” Ellis said. “It’s hard to convey what’s been done in the field and how it needs to be processed.”

通过经验丰富的现场人员交叉培训，可以与数据合作，您可以在整理重要数据时会直觉在现场工作人员试图完成的工作。

Similarly, said Ellis, it can be hugely helpful to have the people who are out in the field operating the scanners also able to work the software.

他说：“我看到很多人在现场进行后期处理，因此他们知道自己很好，可以打包一切，或者知道如果他们遇到问题，他们需要重新恢复。”“许多野外人员都开始扮演分析的角色，这是一件好事。您在该领域的人们的生产力要高得多。”

交叉训练还有助于填补地理空间专业的劳动差距。埃利斯说：“很难找到好人，因此，如果在该领域进行集合的团队可以管理大多数后处理，并达到可以认证的地步，这有助于保持项目的良好状态。”

As for the tech, Olson said there’s no need to stress about that. Just make sure you’ve got a lot of multi-terabyte USB drives, which are now extremely inexpensive, and don’t go cheap on your hardware.

“Your standard CAD machine handles this stuff just fine,” Olson said. “The software is starting to catch up now. You don’t really need much to get going. It’s pretty simple. Even your basic laptop can handle it. Sure, you need a decent computer, but we’re an engineering firm, so we had them anyway.”

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A Seamless Workflow

在Pegasus Manager中完成的所有后处理后，工作流程对于将数据集组合起来很简单。运行两辆车的团队都能够实时检查数据和图像以进行覆盖范围，然后使用轨迹调整模块将所有数据汇总在一起并限制调查控制。Pegasus软件使用自动化功能提取和其他自动化功能来使后处理快速有效。

从那里开始，Horrocks能够将微观的文件和TopoDot文件传递到爱达荷州。（软件出口到所有通用行业标准格式。）

奥尔森说：“为了解决所有这些数据，四人组成的团队大约需要一周半的时间来提取完整​​的调查。”“它比几年前快得多。”

Leica Geosystems的Jason Ellis为这份工作提供了技术支持，因为他已经为调查团队做了数十年。在这种情况下，他也对收集速度印象深刻。

由于他们的互补专业知识，期望管理和良好的沟通，这两家工程公司取得了成功。鉴于提前进行良好的沟通和相对平稳的操作，团队能够在没有头痛的情况下将测深和激光雷达数据组合在一起。

本文的完整版本发表在xyHt magazine2019年10月。