Yosemite National Park - Features Waterbodies LiDAR 2019 - Open Data

Product: Hydroflattened breaklines covering the Yosemite National Park USGS 3DEP Lidar project area. Geographic Extent: This dataset and derived products encompass an area covering approximately 803,364 acres of the western Sierra Nevada mountain range of Central California. Dataset Description: Dataset Description: Lidar flight line swaths were processed to create 3,437 classified LAS 1.4 files delineated in 1,000m x 1,000m tiles tiles. Each LAS file contains lidar point information, which has been calibrated, controlled, and classified. Breaklines were developed using an algorithm which weights lidar-derived slopes, intensities, and return densities to detect the water's edge. The water's edge was then manually reviewed and edited as necessary. Lakes were assigned a consistent elevation for an entire polygon while rivers were assigned consistent elevations on opposing banks and smoothed to ensure downstream flow through the entire river channel. Additional products include classified LAS files, intensity images, tiled 0.5 meter contours and tiled bare earth surface models. Ground Conditions: Acquisition occurred free of smoke, fog and cloud during a time frame absent of unusual flooding or inundation and during leaf off conditions when possible. However, due to its high elevation, there are a few patches of snow throughout the dataset which were classed accordingly and delineated by a snow polygon. IRMA Data Store Reference产品：覆盖美国优胜美地国家公园美国地质调查局（USGS）3DEP激光雷达（Lidar）项目区域的Hydroflattened断点线数据集。地理覆盖范围：本数据集及其衍生产品覆盖加利福尼亚州中部内华达山脉西部约803,364英亩的区域。数据集说明：对激光雷达飞行航线条带进行处理，生成3437个分类LAS 1.4格式文件，以1000米×1000米瓦片进行划分。每个LAS文件均包含经过校准、控制点校正与分类的激光雷达点云数据。断点线通过算法生成，该算法对激光雷达衍生的坡度、强度与回波密度赋予权重，以检测水岸线；随后对水岸线进行人工复核与必要编辑。为每个完整湖泊多边形赋予统一高程，而为河流两岸赋予一致高程并进行平滑处理，以确保水流沿整个河道顺畅向下游流动。衍生产品还包括分类LAS文件、强度影像、分幅0.5米等高线以及分幅裸土地表模型。地面采集条件：数据采集期间无烟雾、雾气与云层遮挡，且未发生异常洪水或淹没事件，尽可能选择在植被落叶期开展作业。但由于区域海拔较高，数据集内存在少量积雪斑块，已按积雪类别进行分类并以积雪多边形进行标注划分。IRMA Data Store Reference