From concept to feasibility in aerial mapping

从2005年开始，法国海军水文和海洋学办公室（Service Hydrographique etocéanographiquede la Marine [Shom]）和法国国家地理研究所（InstitutgéographiceNational [IGN]）开始进行，作为国家项目Litto3D®的一部分，一系列法国大都会和一些海外领土的沿海调查。

沿海地区当时的描述很差。空气中的测深痛数据用于创建沿海地区的连续高度测定数据集。该项目的目的是为洪水，滑坡和地震制定更好的风险管理预防计划，并支持经济发展战略，环境保护政策和科学研究，这些研究需要了解近岸地形和测深的知识。

From 2007 to 2015, SHOM built a strong expertise in the Airborne LiDAR Bathymetry (ALB) technical field by subcontracting data acquisition to survey companies. In February 2016, the French Ministry of Environment officially decided to finalise the maritime part of the Litto3D® program; up to half of the cost of a regional ALB survey could be directly funded.

This decision opened a new perspective; instead of subcontracting survey companies SHOM could run and operate its own ALB capacity with the guarantee to be financially supported. It was decided to launch a call for proposals on a three-year ALB full service. The selected company would have to provide not only the bathymetric LiDAR system but also the aircraft and its pilots, the training of the laser operators, take care of the maintenances/calibrations, and deal with the administrative support (flight permits, insurance policy, etc.).

Leica Geosystems和Cae Aviation赢得了这种公众招标。

计划映射任务

Leica Geosystems和CAE Aviation动员了他们为SHOM的团队提供全面的理论和实用培训的努力，以了解LIDAR和与此技术相关的软件。

在诺曼底和法国北部进行的第一项调查使用了安装在Cessna Grand Caravan上的机载的多传感器深水测深和地形LIDAR系统的Leica Hawkeye III。

在瑟堡的数据获取期间鹰眼三世captured full waveform in a favourable survey environment; the wind conditions were relatively calm with flat seas and without fog in the survey area. In addition, the Leica MissionPro software with the 3D virtual globe view helped in the preparation and planning for the flights, and theLeica Flightpro飞行管理和传感器控制系统有助于收集数据。

The results of this first topo-bathymetric survey exceeded SHOM’s expectations. The achieved work on morpho-sedimentary cells was impressive. “Leica Geosystems LiDAR technology worked perfectly; no failures occurred during our first mission,” said Yves Pastol, SHOM’s expert on ALB. “Having in our team a Leica Geosystems technician the first weeks of the mission was very instructive. This way SHOM’s crew was able to learn and survey at the same time.”

挑战

Given these positive findings from the Normandy and North France survey, SHOM decided to plan a major operation along the Channel coastline: a coastal survey from Baie du Mont-Saint-Michel (western Normandy) to the Belgian border. This second topo-bathymetric survey will enable SHOM to generate a complete geographical product by mid-2018. The expected coverage goes down to 5 metres isobaths and up to 400 m inland.

This second survey is a real challenge for SHOM; Mont-Saint-Michel is known for the highest tides in Europe. If the flights are correctly timed during low tides, the SHOM team can take advantage of them. The inclement weather might be another obstacle to overcome as well as the turbid coastal waters of the English Channel. The HawkEye III is deployed once again to provide high resolution and accurate deep bathy, shallow bathy and topography data. An important goal in this kind of survey is to have a smooth transition between topographic and bathymetric data.

“The HawkEye III can achieve earth-sea continuity with its various sensors,” said Pastol. “This technology ensures us there will be no gaps in the Digital Terrain Model (DTM), which is essential for our end product.” On the software side, Leica Geosystems also provides theLeica LiDAR Survey Studio (Leica LSS)to pre-process the waveform and position data to create classified point clouds. The SHOM team can review the deep bathymetry, the shallow and the topographic LiDAR data at the same time, including reviewing the images taken at the same location as the point cloud data.

“从一种经济有效的方法来看，与过去的船舶调查相比，Topo和Bathy的调查必须单独进行，我们必须启动复杂的合并数据过程。借助Leica Geosystems技术，这已经不再需要了。”

一种创新的解决方案

激光雷达技术已广泛用于监测各种自然危害。由于捕获的数据的准确性很高，该技术也用于海洋科学领域，包括DTM和测深映射。Hawkeye III是针对最苛刻的调查要求优化的易于使用的传感器。

“ SHOM有责任在困难地区进行调查，而我们与Leica Geosystems的合作伙伴关系通过处理项目的所有其他方面，例如系统安装，校准，技术和航空维护等，使我们放心了。”Shom Litto3D项目经理Yves-Marie Tanguy说。“ Shom的需求是巨大而复杂的，但是我们可以证明Leica Geosystems对我们所有的要求都充满了专业素养的回答。”