EAARL-B Topography—Big Thicket National Preserve: Little Pine Island Bayou Corridor Unit, Texas, 2014

A bare-earth topography Digital Elevation Model (DEM) mosaic for the Little Pine Island Bayou Corridor Unit of Big Thicket National Preserve in Texas was produced from remotely sensed, geographically referenced elevation measurements collected on January 15, 21, 22, 26, 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.美国地质调查局（U.S. Geological Survey）联合国家公园服务局墨西哥湾沿岸网络（National Park Service - Gulf Coast Network），于2014年1月15、21、22、26及30日通过遥感手段获取地理参考高程测量数据，据此生成了得克萨斯州大厚地国家保护区（Big Thicket National Preserve）小松岛贝尤走廊单元（Little Pine Island Bayou Corridor Unit）的裸地表层地形数字高程模型（Digital Elevation Model, DEM）镶嵌数据集。 本次高程测量采用第二代实验型先进机载研究激光雷达（Experimental Advanced Airborne Research Lidar, EAARL-B）：该系统为安装于飞机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。系统通过高频激光束穿透机身底部开口射向地表，记录激光束发射与机载接收反射信号的时间差以解算高程信息。作业时，飞机以约55米/秒的飞行速度、300米左右的作业高度飞越目标区域，形成宽度约240米的激光扫描条带，平均点密度达1.4个/平方米。该系统峰值采样率达15-30千赫，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进行分析后，可为土地开发相关管理决策提供极具价值的辅助工具。