Orthomosaic Image and Digital Surface Model for the Kotzebue B South Beaver Dams and Ponds site, Baldwin Peninsula, Alaska, 08 August 2023

The Arctic Beaver Observation Network (A-BON): Tracking a new disturbance regime project observes beaver engineering across circumarctic treeline and tundra environments during the last half-century by mapping and tracking beaver ponds using remote sensing imagery. Drones are being used to collect baseline data and track beaver dam building and pond evolution over time. This dataset consists of an orthomosaic and digital surface model (DSM) derived from drone surveys on 07 August 2023 at the Kotzebue B South site on the Baldwin Peninsula, Alaska. 121 digital images were acquired from a DJI Phantom 4 Real-Time Kinematic (DJI P4RTK) quadcopter with a DJI D-RTK 2 Mobile Base Station. The mapped area was around 22 hectares (ha). The drone system was flown at 120 meters (m) above ground level (agl) and flight speeds varied from 8-9 meters/second (m/s). The orientation of the camera was set to 90 degrees (i.e. looking straight down). The along-track overlap and across-track overlap of the mission were set at 80% and 70%, respectively. All images were processed in the software Pix4D Mapper (v. 4.9.0) using the standard 3D Maps workflow and the accurate geolocation and orientation calibration method to produce the orthophoto mosaic and digital surface model at spatial resolutions of 5 and 10 centimeters (cm), respectively. Elevation information derived over waterbodies is noisy and does not represent the surface elevation of the feature. A Leica Viva differential global positioning system (GPS) provided ground control for the mission and the data were post-processed to WGS84 UTM Zone 3 North in Ellipsoid Heights (meters).

北极海狸观测网络（Arctic Beaver Observation Network, A-BON）：本项目旨在追踪一种新型扰动机制，通过遥感影像绘制并追踪海狸池塘，以监测过去半个世纪环北极林线与苔原环境中的海狸工程活动。本项目同时采用无人机采集基础数据，实时追踪海狸水坝修筑与池塘随时间的演化过程。本数据集包含2023年8月7日于美国阿拉斯加州鲍德温半岛科茨比B南（Kotzebue B South）站点开展的无人机测绘所生成的正射影像镶嵌图（orthomosaic）与数字表面模型（digital surface model, DSM）。本次测绘采用搭载DJI D-RTK 2移动基站的DJI Phantom 4实时动态定位（DJI Phantom 4 Real-Time Kinematic, DJI P4RTK）四旋翼无人机，共采集121张数字影像。本次测绘区域面积约22公顷（hectare, ha）。无人机飞行高度设置为地面以上120米（above ground level, agl），飞行速度介于8至9米/秒（meters per second, m/s）之间。相机拍摄朝向设置为90度（即垂直向下）。本次测绘任务的航向重叠度与旁向重叠度分别设置为80%与70%。所有影像均在Pix4D Mapper（v.4.9.0）软件中，采用标准三维地图作业流程与精准地理定位及姿态校准方法进行处理，最终生成空间分辨率分别为5厘米（centimeter, cm）与10厘米的正射影像镶嵌图与数字表面模型。水体区域提取的高程信息存在噪声，无法准确反映该水体地物的实际表面高程。本次任务采用徕卡Viva差分全球定位系统（differential global positioning system, GPS）作为地面控制点，所有数据经后处理后采用WGS84坐标系UTM 3号北带投影，以椭球高（单位：米）存储。