Maine Orthoimagery Coastal Penobscot Bay 2024

This dataset consists of true color aerial imagery of the coastline and islands of Penobscot Bay, between Marshall Point of Port Clyde, ME and Brooklin, ME. Imagery was captured at 14.5-cm GSD resolution and used to produce 6” orthorectified imagery with one-foot horizontal accuracy. Imagery collection dates were 6/26/24, 7/8/24, 7/26/24, and 7/27/24, during low tide conditions within two hours of spring tides. Additional atmospheric considerations were complied with including sun angle between 25 degrees and 50 degrees, no more than 10% cloud cover, and less than 10 knots of a maximum predicted wind velocity. Additionally, flights were only dispatched after a precipitation-free period of at least 48 hours. The project area consisted of approximately 3,500 images on 33 flight lines with 60% endlap and 30% sidelap. Airborne GPS and IMU were utilized during the acquisition to improve the aerotriangulation solution. Raw imagery was acquired using the Vexcel Eagle 80-mm Mark 3 mounted on a fixed wing aircraft and flown at an elevation of approximately 9,500 feet. Digital ortho-rectified imagery was created using the raw digital aerial imagery, ground control, aerotriangulation, and a digital elevation model. Existing State of Maine ground control as well as newly collected points were utilized in the aerotriangulation solution for this project. These aerial survey products were created under contract for the State of Maine Department of Environmental Protection. Bluesky Geospatial, subcontractor, captured the raw aerial imagery and produced the digital orthophotos and related products, while James W. Sewall, contractor, provided ground control and verified that project specifications were met.本数据集涵盖美国缅因州波特克莱德马歇尔角至布鲁克林区间内彭诺布斯科特湾（Penobscot Bay）的沿岸与岛屿真彩色航空影像。该影像采集分辨率为14.5厘米地面采样距离（Ground Sample Distance, GSD），并基于此生成了水平精度达1英尺的6英寸正射影像。影像采集时段为2024年6月26日、7月8日、7月26日及7月27日，所有采集工作均安排在春汛前后两小时内的低潮阶段进行。本次采集严格遵循大气与气象规范：太阳高度角介于25°至50°之间，云量不超过10%，最大预测风速低于10节；且仅在连续至少48小时无降水的时段后才会调度飞行任务。本项目作业区域共规划33条飞行航线，累计采集约3500张航空影像，航向重叠率为60%，旁向重叠率为30%。采集过程中搭载了机载GPS与惯性测量单元（Inertial Measurement Unit, IMU），以优化空中三角测量解算效果。原始航空影像由搭载于固定翼飞机的Vexcel Eagle 80-mm Mark 3相机采集，飞行高度约为9500英尺。数字正射影像基于原始航空影像、地面控制点、空中三角测量结果及数字高程模型（Digital Elevation Model, DEM）生成。本次空中三角测量解算同时采用了缅因州现有地面控制点与本次项目新采集的控制点数据。本航空测绘产品为缅因州环境保护部（Maine Department of Environmental Protection）委托项目的产出成果，其中分包商Bluesky Geospatial负责原始航空影像的采集及数字正射影像与相关产品的生产，总承包商James W. Sewall则负责地面控制点采集与项目合规性验证。