Multispectral Orthomosaic Image for the Swan Lake Creek Beaver Dams, Seward Peninsula, Alaska, 12 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 12 August 2022 at the Swan Lake Creek site on the Seward Peninsula, Alaska. 828 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. 4.7.5) 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涌现”研究项目聚焦于在苔原海狸池塘布设野外研究站点，以探究海狸生态工程活动对水文与多年冻土的影响。研究团队借助无人机采集基础数据，并长期追踪海狸坝修筑与池塘演化进程。本数据集包含2022年8月12日，于阿拉斯加州苏厄德半岛天鹅湖溪（Swan Lake Creek）站点开展无人机测绘所获取的多光谱正射镶嵌影像。本次测绘采用DJI精灵4实时动态差分（Real-Time Kinematic, RTK）四旋翼无人机（DJI P4RTK）搭配DJI D-RTK 2移动基站，共采集5个光谱波段的数码影像共计828张。测绘覆盖区域面积约25公顷（ha）。无人机飞行高度设定为距地面120米（agl），并采用悬停定点拍摄模式采集影像。相机拍摄角度设为90度（即垂直向下拍摄）。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%。所有影像均通过Pix4D Mapper软件（v.4.7.5）处理，遵循标准三维地图工作流并采用精准地理定位与姿态校准方法，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。研究人员使用MicaSense校准反射板拍摄的影像，在Pix4D内置的指数计算器工具中完成各光谱波段的辐射定标与辐射处理。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，并将数据后处理至WGS84 UTM 3N坐标系。