Multispectral Orthomosaic Image for the Glacier Creek Road Beaver Dams and Ponds, Seward Peninsula, Alaska, 14 August 2022

Emergence of beavers as ecosystem engineers in the New Arctic project focuses on establishing field sites at tundra beaver ponds to study the implications of beaver engineering on hydrology and permafrost. Drones are being used to collect baseline data and track beaver dam building and pond evolution over time. This dataset consists of a multispectral orthomosaic derived from drone surveys on 14 August 2022 at the Glacier Creek Road site on the Seward Peninsula, Alaska. 4,146 digital images from five spectral bands 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 50 hectares (ha). The drone system was flown at 120 meters (m) above ground level (agl) and images were captured using the hover and capture at point mode. 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. 4.7.5) using the standard 3D Maps workflow and the accurate geolocation and orientation calibration method to produce the multispectral orthophoto mosaic at a spatial resolution of 10 centimeters (cm). Images of a MicaSense calibrated reflectance panel were used for radiometric processing and calibration of each spectral band in the Index Calculator in Pix4D. 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."新北极区域河狸作为生态系统工程师的涌现"（Emergence of beavers as ecosystem engineers in the New Arctic）项目聚焦于在苔原河狸池塘设立野外监测站点，以探究河狸生态工程活动对水文循环与多年冻土的影响。本研究依托无人机采集基础观测数据，并长期追踪河狸坝建造过程与池塘演化动态。本数据集包含由2022年8月14日对阿拉斯加州苏厄德半岛冰川溪路站点开展的无人机航测所生成的多光谱正射影像镶嵌图（multispectral orthomosaic）：本次航测使用搭载DJI D-RTK 2移动基站的DJI Phantom 4 实时动态差分（Real-Time Kinematic, RTK）四旋翼无人机（以下简称DJI P4RTK），共采集5个光谱波段的数字影像4146张，测绘区域面积约50公顷（ha）。本次航飞作业的飞行高度设定为距地面120米（agl，above ground level），采用悬停定点拍摄模式采集影像，相机朝向固定为90度（即垂直向下拍摄）。本次航测任务的航向重叠度与旁向重叠度分别设置为80%与70%。所有影像均通过Pix4D Mapper（v.4.7.5）软件，采用标准三维地图工作流与精准地理定位、姿态校准方法进行后期处理，最终生成空间分辨率为10厘米（cm）的多光谱正射影像镶嵌图。本研究使用MicaSense校准反射板采集的影像，在Pix4D内置的指数计算器（Index Calculator）中完成各光谱波段的辐射定标与校准处理。本次任务采用徕卡Viva差分全球定位系统（Leica Viva differential global positioning system, GPS）提供地面控制点数据，并将所有定位数据后处理至WGS84 UTM北3区（WGS84 UTM Zone 3 North）坐标系。