Multispectral Orthomosaic Image for Upper Nome River (MP31) Beaver Ponds, Seward Peninsula, Alaska, 02 August 2023

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 02 August 2023 at the Upper Nome River, MP31, site on the Seward Peninsula, Alaska. 1812 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 25 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. 4.8.4) 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.

《新北极地区海狸作为生态系统工程师的涌现》研究项目聚焦于在苔原海狸池塘设立野外监测站点，以探究海狸生态工程活动对区域水文与永久冻土的影响。研究团队使用无人机采集基线数据，并动态追踪海狸水坝建造与池塘的演化过程。本数据集包含2023年8月2日于阿拉斯加州苏厄德半岛诺姆河上游MP31点位开展的无人机航拍所生成的多光谱正射影像镶嵌图。本次航拍搭载大疆精灵4实时动态（DJI Phantom 4 Real-Time Kinematic, DJI P4RTK）四旋翼无人机与大疆D-RTK 2移动基站，共获取5个光谱波段的1812张数字影像。航拍覆盖区域面积约25公顷（ha）。无人机飞行高度设定为距地面120米（agl），采用悬停定点拍摄模式采集影像，相机朝向设为垂直向下（即90°俯拍）。本次航拍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.4.8.4）软件，采用标准三维地图工作流，结合精准地理定位与姿态校准方法完成处理，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。研究团队使用MicaSense校准反射板拍摄的参考影像，在Pix4D的指数计算器（Index Calculator）中对每个光谱波段开展辐射处理与定标。本次任务采用徕卡Viva差分全球定位系统（GPS）作为地面控制点，并将所有观测数据后处理至WGS84 UTM第3北带坐标系（WGS84 UTM Zone 3 North）。