EAARL-B Topography-Big Thicket National Preserve: Big Sandy Creek Corridor Unit, Texas, 2014

A bare-earth topography Digital Elevation Model (DEM) mosaic for the Big Sandy Creek Corridor Unit of Big Thicket National Preserve in Texas was produced from remotely sensed, geographically referenced elevation measurements collected on January 19, 21, 22, 29, and 30, 2014 by the U.S. Geological Survey, in cooperation with the National Park Service - Gulf Coast Network. Elevation measurements were collected over the area using the second-generation Experimental Advanced Airborne Research Lidar (EAARL-B), 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 55 meters per second at an elevation of approximately 300 meters, resulting in a laser swath of approximately 240 meters with an average point density of 1.4 points per square meter. A peak sampling rate of 15-30 kilohertz results in an extremely dense spatial elevation dataset. More than 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.

为美国得克萨斯州大厚地国家保护区（Big Thicket National Preserve）的大桑迪溪走廊单元制作的裸土地形数字高程模型（Digital Elevation Model, DEM）镶嵌数据集，由美国地质调查局联合国家公园服务局墨西哥湾沿岸网络，基于2014年1月19、21、22、29及30日采集的遥感地理参考高程测量数据制作完成。本次高程测量采用第二代实验先进机载研究激光雷达（Experimental Advanced Airborne Research Lidar, EAARL-B）完成，该系统为安装于航空器机身底部开口处的脉冲激光测距装置，可同步获取地面高程、植被冠层及海岸地形数据。系统通过航空器机身底部的开孔向地表发射高频激光束，并记录激光束发射与机载端接收反射激光信号之间的时间差。作业时航空器以约55米/秒的飞行速度、约300米的飞行高度飞越目标区域，所形成的激光条带宽度约240米，平均点密度达每平方米1.4个点。该激光系统峰值采样率可达15至30千赫，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。对该区域生成的高程地图开展分析，可作为土地开发相关管理决策的重要辅助工具。