用测深痛保护人和财产

作者：Renata Barradas Gutiérrez

日本是一个大型群岛，位于一个活跃的融合区域，毗邻太平洋一侧的深沟，以及日本海的许多断层和峡谷。由于其地理和复杂的地形，日本是地球上最暴露的自然危害国家之一，例如海平面上升，洪水，地震和海啸。人口增长，气候变化和经济发展，此外，正在威胁人们，基础设施以及位于几条河流和海岸平原的生态系统。

Despite its great exposure to hazards, ranked by the 2016 World Risk Report as the 17^th日本大多数容易发生的灾难风险国家通过调整长期准备策略并采取行动来了解其地形和环境，从而降低了其脆弱性。

Aero Asahi Corp’s (AAC) mission is to protect life and property from any disaster or incident by using the latest hardware and software technologies. This aviation and spatial information services company is aware that data is required to mitigate the risks in the event of future disasters. To support disaster management and prevention, maintain infrastructure and map properties, AAC uses mobile mapping, aerial photo surveys, and LiDAR topographic and bathymetric surveys.

在执行任务

河流在日本,直接由专业管理t, have a total length of approximately 8,800 kilometres and are characterised by a deep V-shaped rinsing from steep forests. The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) manages and monitors the rivers of the Nippon country. To monitor the river bed deformation every 200-metre pitch, MLIT used in the past an echo sounder performing cross-sectional terrain surveys every five years on the major rivers. To防止灾难并加快任何恢复努力，AAC现在提供了测深和地形数据和地图to MLIT’s river management bureau.

AAC collects data precisely and safely using the Leica Chiroptera II bathymetric and topographic LiDAR sensor mounted in a helicopter, covering large areas in just minutes. The Chiroptera II’s near-infrared (NIR) wavelength for topographic and a green wavelength for bathymetric data collection allows the team to map and measure depth in shallow coastal zones and inland freshwater bodies, such as rivers and lakes and surrounding flood-plains.

“We collect and analyse all the precise data to provide information ready to use, such as deformation, sediment, cross sections, erosions, and bank height for management authorities. Since the Chiroptera II combines a topographic and bathymetric lidar, we can seamlessly measure from water to land – this is particularly useful when rivers are running浅的，”said Hiroshi Isobe, deputy chief of airborne operations at AAC.

AAC improved the approach used in the past by complementing the data captured with Chiroptera II with an in-house solution – an echo sounder “Underwater Inspector.” The team tested this approach on the government-controlled rivers in Japan. This combined survey helped the team to create aseamless dense point cloud regardless of the water depth, turbidity, colour, temperature and PH of the river.

The perks of attaching a LiDAR sensor to a helicopter

Mountains cover 73 per cent of the land of the rising sun. When performing aerial surveys in mountainous terrain, AAC attachesChiroptera II到AS350-B3直升机的背面，垂直稳定器的顶部具有GNSS天线，以获得具有较高密度的地理参与点云. AAC is convinced that the variable airspeed, the flexible base location, the shorter turning time and the very low-altitude that can be flown with a helicopter is preferable than the quieter flight with long range and extended flight time that a fixed wing plane provides.

“在较慢的空速中获得的点云很密集。与直升机一起飞行，我们可以收集带有回声声音的船长船无法进入和控制日本陡峭地形的海拔高度的水深，”said Isobe.

多个应用程序

A wide range of deliverables like digital surface and地形模型，分类点云，正吞和GIS层can be created using Chiroptera II’s collected data to develophydrological models to analyse the water flows, drainage management, flood control and support land planning activities. The team of experts uses Leica LiDAR Survey Studio (LSS) to understand the river’s topography and create accurate risks analysis.

AAC提供的定期横截面调查可用于多种应用，包括：

• Flood mapping
• 环境建模和监视
• Visualise the riverbed deformation ground and underwater
• 得出流量
• Accuracy controls for water level applications.

Predicting the unpredictable

To protect populations living near water bodies authorities need to study the topography of a river and its surrounding area to monitor changes and predict the behaviour of a water body under different conditions. Airborne LiDAR bathymetry is an effective method to即使在危险区域和浑浊的水域进行调查，创建了沿海和内陆水体的准确而精确的模型.

“The detailed topographic data obtained from aerial laser surveys is used to simulate flooding and make hourly predictions of how floods spread. The simulation results and infrastructure information maps are analysed to provide optimum data for crisis management, such as evacuation routes, evacuation shelters and affected population. In addition, stereo matching of aerial photos during flooding is used to analyse surface flow rate and flow direction,”结论是尤比特。