EAARL-B Topography—Big Thicket National Preserve: Canyonlands and Upper Neches River Corridor Units, Texas, 2014

A first-surface topography Digital Surface Model (DSM) mosaic for the Canyonlands and Upper Neches River Corridor Units of Big Thicket National Preserve in Texas was produced from remotely sensed, geographically referenced elevation measurements collected on January 11, 15, 17, 18, 21, 23, 25, and 29, 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密林国家保护区（Big Thicket National Preserve）的峡谷地（Canyonlands）与上内皮奇斯河走廊单元（Upper Neches River Corridor Units）制作的第一表面地形数字表面模型（Digital Surface Model, DSM）镶嵌图，由美国地质调查局（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），基于2014年1月11、15、17、18、21、23、25及29日采集的遥感地理参考高程测量数据生成。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。系统通过航空器机身底部的开口向地表发射高频激光束，并记录激光束发射与机载接收反射激光信号之间的时间差。作业时，航空器以约55米每秒的速度飞越目标区域，飞行高度约300米，由此形成宽度约240米的激光条带，平均点密度为每平方米1.4个点。该系统峰值采样率达15至30千赫，可生成极为密集的空间高程数据集。单次3至4小时的作业任务即可轻松完成超过100公里海岸线的测绘工作。当对该数据集生成的区域高程地图进行分析时，其可作为土地开发管理决策的实用工具。