空气扫描技术的改善提高了生产力
Leica TerrainMapper遇到了大面积映射的挑战。
Author: Linda Duffy
通过改进的扫描功能和功能，满足了对空中激光雷达的需求增加，这些功能在更少的时间内会在较大的区域上产生密集的点云。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).
A colorized 3D point cloud image (top) can be compared to a bare-earth image (bottom) looking northwest on U.S 26 near Wind River Lake in Teton County, Wyo.
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。
Expectations for density and accuracy continue to rise to match the enhanced capabilities of LiDAR sensors. Incremental improvements in performance culminated in the release of the Leica TerrainMapper, a linear-mode sensor that allows very dense point clouds to be collected at a higher altitude, greatly reducing acquisition time.
“大区域映射,效率真的支付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。
这个裸露的点云图像显示在未遮挡景色的景观轮廓中，在美国怀俄明州特顿县的布鲁克斯湖溪瀑布附近的美国26号北部的云点云图像中显示。
Meeting and exceeding the specs
每个项目都有最低数据要求，具体取决于预期的应用程序。例如，USGS QL1数据必须至少为每平方米至少8点（PPSM），其均方根误差（RMSE）不超过10.0厘米（CM）。其他标准可能包括叶子，没有雪，没有积水和没有雨。在温带气候中，落叶树和雪是障碍。在热带和亚热带气候中，云和雨水通常是一个问题。由于许多地理区域中的挑战性条件，在有限的飞行窗户上收集有效的数据对于完成工作至关重要。
2019年，怀俄明州交通运输部（WYDOT）与伍尔珀特（Woolpert）签约，在西北怀俄明州（Wyoming）沿着靠近黄石国家公园的西北怀俄明州（Wyoming）沿着大陆鸿沟的10英里延伸地图地图。Woolpert以50 ppsm收集了LiDAR，并用集成的Leica RCD30航空相机同时收集了点云。最终的数字地形模型（DTM）和三角形的不规则网络（TIN）模型为WYDOT提供了一个基线，以确定地球随时间移动的滑动运动，体积和速率。Wydot进行了独立的检查，并比较了来自现场收集点的120多个单个点云高程。平均高度差为3.6 cm超过了所需的5 cm垂直精度。
The TerrainMapper has also proven effective on linear 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.
Seppi说：“在高浮雕地形中，我们通过更高飞行而不适应许多不同的高度来实现更高的效率。”“对于公用事业的工作，在远高于线的高海拔地区飞行更安全，其额外好处是捕获更多的周围区域。”
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.”
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.
Seppi说：“ HXMAP使我们能够更加敏捷，并随时适应变化。”“当我们有关键的截止日期时，我们可以轻松地转移处理以从其他项目分配HXMAP资源。HXMAP就像一个黑匣子，它会自动在幕后执行其作品。”
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。
Continuous improvement
The Leica TerrainMapper is the next generation of LiDAR sensors after the highly successful ALS80 series. The sensor system increases data collection rate versus flying height, improves flight planning, and achieves even point distribution. The enhanced productivity saves time and money, while the higher pulse rate, greater laser power and gateless technology contributes to higher point density.
塞皮说：“莉卡·地理系统的传感器一直在变得更好。”“从ALS80的TerrainMapper的表现跃升非常重要。我们发现圆形扫描模式具有很大的优势，例如线到线的校准和音高调整。飞行更高，更快地提高了我们的效率200-400％。自1989年以来，Leica Gebob综合app下载osystems产品一直是我们传感器机队的骨干。”
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.
