2029年，美国加利福尼亚州将看到该国第一个高速铁路系统的开放。The project, commissioned by the California High-Speed Rail Authority, will connect San Francisco and the Los Angeles basin - the state’s so-called ‘mega-regions’ - allowing customers travelling the route to reach their destination in under three hours with speeds exceeding 200 miles (322km) per hour.
(This story is brought to you by senseFly)
加利福尼亚运输工程公司JL Paterson＆Associates（JLP，现为Jacobs Engineering Group）在2015年初被当局邀请，为洛杉矶的工程设计工作送往阿纳海姆走廊。然而，JLP前副总裁MarcCañas及其同事面临的挑战是，该项目成立之前，这条路线不存在调查数据。这意味着，在工作开始之前，有必要调查整个区域：30英里（48公里）的长达1,500英尺（4.57亿）宽的活动铁路走廊，每天可以看到多达100列火车。
选择正确的工具
With a significant area to map and a tight timeline to work to, it was vital for the team at JLP to collect the data they needed accurately, quickly and with minimal disruption to the corridor’s day-to-day operations. Traditional surveying options, such as aerial mapping via a manned flight and ground-based surveying, were considered in the early stages; however, these were not able to meet the stringent time or flexibility requirements. Ground-based surveying techniques required lengthy permits to access the site and would have experienced continuous disruption due to train traffic. Alternatively, while a manned aerial flight over the area would have avoided the necessity for disruption, it would have taken eight to ten weeks to collect and process the data. The team also required a more in-depth, three-dimensional data model to best inform project logistics and guide decision-making, leading them to conclude that unmanned aerial vehicle (UAV) technology would be the best solution.
先前使用Sensefly Ebee无人机在小型项目上使用，Cañas和他的同事选择使用Sensefly Ebee RTK（调查级映射无人机）。EBEE RTK旨在捕获航空摄影和映射数据，可以实时创建高度准确的3D模型，并因其专业，调查级质量和便携性而选择。使用这项技术，团队可以在现场并在几分钟之内飞行，而无需复杂的启动系统或对铁路流程和操作的破坏。该软件的地理围栏功能可通过预装的情感软件获得，也是该决定的重要因素，因为它可以通过提前启用飞行计划来提高飞行过程中车辆的安全性。
Overcoming obstacles
而熟悉无人机技术的试验ence of UAV technology on a large scale for surveying was limited. In addition, stringent Federal Aviation Authority (FAA) regulations meant that, although JLP owned two eBee RTKs when the project was carried out, the team was only able to fly one aircraft at a time to collect data. The result of this was that, in the early stages of the project, a significant amount of trial and error was required to identify any factors that might interfere with data collection and to enable the team to integrate the software as seamlessly as possible into workflow and operations.
基于这些试验，JLP随后创建了一系列1,500英尺（457m）乘5200英尺（1,585万）飞行多边形区域，重叠面积约为300英尺（91m），这构成了地面控制点（GCPS）的基础。尽管RTK无人机通常不需要GCP，但项目环境的性质意味着RTK网络是不可靠的，并且冒着在某些领域退出的风险。除了帮助完善执行任务的执行外，最初的试验还表明，所选方法适合JLP的走廊目标并在现场优化时间。
The team at JLP also had to take into consideration the challenge posed by FAA regulations on maximum elevation levels, which specify that UAV flight elevation cannot exceed 400 feet (122m) above take-off altitude (ATO). To overcome this and obtain high-quality orthomosaic aerial imagery, JLP used the eMotion software to set a 3.6cm (1.4in) per pixel ground resolution. The eMotion program was also used to incorporate elevation data, which helped to ensure that all flights remained at the same altitude above the ground and provided consistent, reliable data.
然而，对于JLP而言，所有最大的挑战可能是，加利福尼亚铁路走廊周围的区域被严重城市化，这意味着该团队的最初地面计划在实践中并不总是很好地转移。例如，当识别起飞和起飞地点时，实际上，在办公室中看起来像合适的位置通常被高架电线或路灯所阻塞，甚至被卫星图像上尚不可见的建筑物所阻塞。结果，有必要适应环境，最终的GCP在项目开始前两周就在周围的街道上绘制。
On the right track
With all 82 GCPs finalised, the team at JLP was able to pave the way for the beginning of the data collection process. To map the 30-mile corridor—an area of 61 square miles (158km2） - JLP将其三名员工部署到该地点，总共飞行了41架航班。平均飞行时间为28分钟，平均飞行高度为200英尺（61m），捕获了11,800张图像。JLP团队的其他三名成员使用Pix4Dmapper Pro软件在短时间内下载并处理了这些功能 - 都在JLP办公室的舒适度中。
By using the senseFly eBee RTK, JLP was able to pull together highly accurate, professional-quality surveying data of the Los Angeles to Anaheim corridor of the California high-speed railroad in less than one month – a job that would have taken more than 18 weeks with traditional surveying techniques and cost twice as much if using a manned aircraft. The team collected ortho-rectified images at 1.5 inches (3.8cm) per pixel – twice the resolution of even the best manned aerial product – and was able to achieve accuracy of one to two inches (2.5 to 5cm) for both vertical and horizontal.
JL Paterson＆Associates国家货运铁路副总裁MarcCañas（JLP，现为Jacobs Engineering Group）：
“Since the completion of the California high-speed rail mapping project, JLP has put its senseFly eBee RTKs to work in a further 15 projects, including construction monitoring and engineering. These operations have hugely benefited from having access to large amounts of in-depth, accurate data in the early stages – in some instances helping to prove the financial viability of a project."
“It is clear that UAV technology has the potential to transform the way that surveying data is used and collected and can be an excellent tool to revolutionise the efficiency and effectiveness of business operations and workflow. While the project was a learning curve for myself and my team, our initial investment, both in terms of financial ROI and training time for our employees, has been worth it many times over.”
