空气扫描技术的改善提高了生产力

Author: Linda Duffy

Increased demand for aerial LiDAR is being met with improved scanning features and functionality that produce denser point clouds over larger areas in less time. As an early adopter of scanning technology, Woolpert, the fastest-growing architecture, engineering and geospatial (AEG) firm in the US, has owned and operated every product in Leica Geosystems’ LiDAR series since the ALS40 was released in 2002. Woolpert purchased its first Leica TerrainMapper in early 2019 and has since acquired three more. Today, the TerrainMapper is Woolpert’s preferred technology for large area mapping and difficult terrain, including Department of Transportation (DOT) projects and federal programs such as the United States Geological Survey (USGS) 3D Elevation Program (3DEP).

海拔数据的需求

空中激光雷达数据是许多应用程序的宝贵信息来源，例如3D城市建模，基础设施开发，沿海和自然危害监测以及环境保护。正在努力建立当前的国家激光雷达数据集，并且也有许多本地和区域实体投资于激光雷达的覆盖范围。

对密度和准确性的期望不断提高，以符合激光雷达传感器的增强功能。在Leica TerrainMapper的释放中，性能的增量改进是一种线性模式传感器的释放，该传感器允许在较高高度收集非常密集的点云，从而大大减少了采集时间。

“With large area mapping, efficiency really pays off,” says Joseph Seppi, vice president and geospatial sector leader at Woolpert. “Our projects can exceed 30,000 square miles, even 100,000 square miles, so the ability to fly at a higher altitude at a faster speed makes TerrainMapper an extremely efficient option.”

TerrainMapper能够在300米（M）至5,500 m之间的飞行高度上收集LiDAR，并在飞行高度达到2公里（km）处提供USGS LIDAR质量0（QL0）数据。这种出色的效率水平非常适合更大的区域或国家地图项目，在该项目中，运营成本对更新频率产生重大影响。

Meeting and exceeding the specs

Every project has minimum data requirements depending on the intended application. For example, USGS QL1 data must be at least 8 points per square metre (ppsm) with a Root Mean Square Error (RMSE) not exceeding 10.0 centimetres (cm). Other criteria may include leaf-off, no snow, no standing water, and no rain. In temperate climates, deciduous trees and snow are obstacles. In tropical and subtropical climates, clouds and rain are often a problem. Due to challenging conditions in many geographic areas, efficient data collection during limited flying windows is crucial for getting the job done.

In 2019, the Wyoming Department of Transportation (WYDOT) contracted with Woolpert to map three landslide areas along a 10-mile stretch of the Continental Divide in northwest Wyoming, close to Yellowstone National Park. Woolpert collected LiDAR at 50 ppsm and colourised the point cloud with imagery collected simultaneously with the integrated Leica RCD30 aerial camera. The final digital terrain models (DTMs) and triangulated irregular network (TIN) models provided WYDOT with a baseline to determine the slide movement, volume and rate at which the earth is moving over time. WYDOT performed an independent check and compared over 120 individual point cloud elevations from field collected points. The average elevation difference of 3.6 cm exceeded the requested 5 cm vertical accuracy.

林TerrainMapper也被证明有效ear utility projects and powerline rights-of-way and successfully measures sag on elevated power lines. Even while flying faster and higher than other sensors, the TerrainMapper returns the necessary point density for a variety of projects.

“In high relief terrain we achieve greater efficiency by flying higher without adjusting to as many different altitudes,” Seppi stated. “And for utility work, it is safer to fly at a high altitude far above the lines, with the added benefit of capturing more of the surrounding area.”

伍尔珀特（Woolpert）在2019年与TerrainMapper一起在各个州飞行了10多个USGS项目。在佛罗里达州和俄亥俄州等州，尽管天气状况，但高速批量的集合在一个飞行季节内完成了映射项目。

“The weather in some places can be challenging, leaving us with fewer days to work, so the high-volume collection capability of the TerrainMapper helps us finish the project quickly and maintain consistency,” Seppi continued. “Also, the point distribution, patterns and excellent intensity returns from this sensor are extremely beneficial for many feature extraction uses.”

This zoomed-in contour map shows features such as pavement, pipes, and a culvert near Wind River Lake.

采集和处理集成

The post-processing workflow is another area where efficiency impacts overall project costs. Woolpert uses the Leica HxMap multi-sensor processing platform, which is designed to streamline the handling of TerrainMapper data. HxMap processes, calibrates, and registers LiDAR point clouds while simultaneously processing image sensor data and colourising the point cloud. With help from HxMap, Woolpert delivers fully processed classified point clouds that meet strict project specifications for accuracy and density.

“HxMap allows us to be more agile and adapt on the fly to changes,” says Seppi. “We can easily shift processing around to allocate HxMap resources from other projects when we have a critical deadline. HxMap is like a black box that automatically performs its work behind the scenes.”

HXMAP专为使用TerrainMapper数据而设计，它利用集成的扫描仪/相机系统的优点来生成一个单个接口中的所有空中数据产品。bob综合app下载HXMAP提供嵌入式空中三角剖分，并为大型倾斜成像项目，全国矫正项目以及大型或小型激光雷达项目提供解决方案。

The Wyoming Department of Transportation translated the lidar data provided by Woolpert into a variety of graphics, including a digital terrain model of the area near Wind River Lake.

连续的提高

Leica TerrainMapper是在非常成功的ALS80系列之后的下一代激光雷达传感器。传感器系统提高数据收集速率与飞行高度，改善飞行计划，并达到偶数分布。增强的生产率节省了时间和金钱，而较高的脉搏率，更高的激光功率和无元技术则有助于更高的点密度。

“Leica Geosystems sensors just keep getting better,” Seppi says. “The performance jump to TerrainMapper from ALS80 was significant. We find the circular scan pattern has a lot of advantages, such as line-to-line calibration and adjustment for pitch. Flying higher and faster boosts our efficiency 200-400%. Leica Geosystems products have been the backbone of our sensor fleet since 1989.”

Demand for 3D LiDAR data is on the rise, which makes timely acquisition and processing increasingly important. The tight integration of TerrainMapper with the HxMap workflow expedites the entire process, from data download to product generation, to support faster turnaround on every mapping project.