结合了快速形态调查的测深量和激光雷达数据
Case study
作者：Sam Pfeifle
当它到达州线，将华盛顿与爱达荷州分隔开来时，蛇河叉，一个tine流向南部，沿边界的蛇流向南部，另一个尖端作为蛇的开始。任何乘船向东行驶的人都会迅速遇到Clearwater Memorial Bridge，这是一座大约228米长的桥梁，专用于第二次世界大战的退伍军人。
这座桥开业于1951年春季，被联邦政府指定为十多年前，主要是因为养活了它的道路，这些道路不再适合每天处理桥梁的交通。
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.
工作第一次下降Horrocks Engineers, which has 15 offices throughout the western United States, including three in Idaho. Collecting survey data for the bridge and surrounding roadways was a standard job for their mobile mapping unit, said Lonnie Olson, principal and survey manager at Horrocks, but the project also called for bathymetric data for the river bottom and bridge substructure.
奥尔森说：“他们想看看桥桩周围的冲刷。”“他们正在寻找的途径之一是保持子结构和大部分桥梁本身。”
He knew that adding multibeam sonar data to the mobile mapping cloud data would give the resulting topo consistent, fine-grained, accurate data from the river bottom on up, but there was a problem: Horrocks doesn’t have a multibeam sonar unit.
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。”
幸运的是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。
奥尔森（Olson）决定与Spicer项目测量师Nathan Shepherd接触，并在工作中结合了部队，这是他第一次将其分包给另一个测量团队。
一天完成
恐怖将驱动桥梁和周围的道路。Spicer会驱车河流以将所有东西放在水线，河岸和桥梁的下面。然后，他们将数据拼接在一起，提取平面计算学以创建表面模型和地形调查。
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。
Still, it was all done in a day.
All told, it took about three days to set up the full control network for the job, then four days onsite preparing and doing the actual scanning, for a total of seven days in the field— significant time savings compared to traditional methods.
“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.”
移动映射的后台效果
You’ve probably heard the horror stories: “Mobile mapping creates so much data it’s impossible to manage!” “Who needs a survey team when all you have to do is drive a scanner around?”
当然，搬进移动映射的确需要后台调整，但是如果您为他们做准备并为您的员工提供培训，它们应该相对易于管理。
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。亚搏苹果appHorrocks的校长和调查经理Lonnie Olson说，这绝对影响了他的劳动力。
他说：“我们的一些现场工作人员在室内过渡。”“而且我有一支由前高级CAD技术组成的团队，我们已经训练过进行调查工作。我们已经能够在内部完成大多数后处理工作。”
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。
同样，埃利斯说，让在现场操作扫描仪的人也能够使用该软件，这可能非常有帮助。
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。”
Cross-training also helps fill the labour gap in the geospatial profession. “It’s hard to find good people, so if the team doing the collection in the field can manage the majority of the post-processing and get to the point where it can be certified, that helps keep projects on track,” Ellis said.
至于这项技术，奥尔森说，无需对此强调。只要确保您拥有很多多端的USB驱动器，这些驱动器现在非常便宜，并且在硬件上也不便宜。
“你的标准CAD机器处理这些东西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.”
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。
From there, Horrocks was able to deliver the MicroStation and TopoDOT files to the Idaho DoT. (The software exports to all common industry standard formats.)
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。
A full version of this article was published inxyHt magazine2019年10月。
