Multispectral Orthomosaic Image for the South Fork Serpentine River Beaver Dams and Ponds, Seward Peninsula, Alaska, 15 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 15 August 2022 at the South Fork Serpentine River site on the Seward Peninsula, Alaska. 3,654 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 86 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.

《新北极地区海狸作为生态系统工程师的崛起》研究项目聚焦于在苔原海狸池塘布设野外监测点位，以探究海狸的生态工程活动对水文与多年冻土的影响。研究团队将使用无人机采集基础基准数据，并长期追踪海狸水坝修筑与池塘的动态演化过程。本数据集源自2022年8月15日对阿拉斯加州苏厄德半岛蛇纹石河支流（South Fork Serpentine River）监测点位开展的无人机航拍作业，包含生成的多光谱正射影像镶嵌图（multispectral orthomosaic）。本次航拍搭载DJI Phantom 4 实时动态差分（Real-Time Kinematic, RTK）四旋翼无人机（DJI P4RTK）与DJI D-RTK 2移动基站，共获取5个光谱波段的数字影像共计3654张。航拍覆盖区域面积约86公顷（ha）。无人机飞行高度设定为距地面120米（above ground level, agl），并采用悬停定点拍摄模式采集影像。相机朝向设置为90度，即垂直向下拍摄。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. 4.7.5）软件，采用标准3D地图处理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为10厘米（cm）的多光谱正射影像镶嵌图。研究借助MicaSense校准反射板的拍摄影像，在Pix4D的指数计算器（Index Calculator）模块中完成各光谱波段的辐射定标与辐射校正。本次任务采用Leica Viva差分全球定位系统（differential global positioning system, GPS）作为地面控制点，并将数据后处理至WGS84 UTM 3N（WGS84 UTM Zone 3 North）坐标系。