EAARL Coastal Topography--Dauphin Island, Alabama, 2010: Bare Earth

ASCII XYZ point cloud data were produced from remotely sensed, geographically referenced elevation measurements by the U.S. Geological Survey (USGS). Elevation measurements were collected over Dauphin Island, post-Tropical Storm Bonnie (July 2010 tropical storm), using the National Aeronautics and Space Administration (NASA) Experimental Advanced Airborne Research Lidar (EAARL), a pulsed laser ranging system mounted onboard an aircraft to measure ground elevation, vegetation canopy, and coastal topography. The system uses high-frequency laser beams directed at the Earth's surface through an opening in the bottom of the aircraft's fuselage. The laser system records the time difference between emission of the laser beam and the reception of the reflected laser signal in the aircraft. The plane travels over the target area at approximately 60 meters per second at an elevation of approximately 300 meters, resulting in a laser swath of approximately 240 meters with an average point spacing of 2-3 meters. The EAARL, developed originally by NASA at Wallops Flight Facility in Virginia, measures ground elevation with a vertical resolution of 3 centimeters. A sampling rate of 3 kilohertz or higher results in an extremely dense spatial elevation dataset. Over 100 kilometers of coastline can be surveyed easily within a 3- to 4-hour mission. When resultant elevation maps for an area are analyzed, they provide a useful tool to make management decisions regarding land development.

本数据集为ASCII格式XYZ点云数据，由美国地质调查局（U.S. Geological Survey, USGS）基于遥感获取的地理参考高程测量数据生成。数据采集于2010年7月热带风暴邦尼过境后的多芬岛（Dauphin Island），采集设备为美国国家航空航天局（National Aeronautics and Space Administration, NASA）研发的实验先进机载研究激光雷达（Experimental Advanced Airborne Research Lidar, EAARL）——一款搭载于航空器的脉冲激光测距系统，可用于测量地面高程、植被冠层与海岸地形。该系统通过航空器机身底部的开口向地球表面发射高频激光束，并记录激光束发射时刻与机载平台接收反射激光信号时刻之间的时间差。航空器以约60米/秒的飞行速度、约300米的飞行高度飞越目标区域，形成宽度约240米的激光扫描带，平均点间距为2-3米。EAARL最初由NASA位于弗吉尼亚州的沃洛普斯飞行设施（Wallops Flight Facility）研发，其地面高程测量的垂直分辨率可达3厘米。当采样率达到3千赫兹及以上时，可生成密度极高的空间高程数据集。单次3至4小时的飞行任务即可轻松完成超过100公里海岸线的测绘工作。对某一区域生成的高程地图进行分析后，可作为土地开发相关管理决策的实用辅助工具。