t20r10tree point

This layer provides an approximate inventory of tree center points for King County in 2021. Tree points were derived through an automated process using 2021 lidar, Ecopia land cover, and NAIP imagery. This layer provides an estimate of tree location and tree height from lidar, tree type (evergreen vs decidious) from lidar intensity, and vegetation health from imagery using NDVI. The points in this layer have not been QA/QC'd or field verified. This layer is not as accurate as a ground inventory would be. However, there are ~101,000,000 trees in King County, so this analysis provides a feasible approximation of tree location and density at a fraction of the cost and effort. Because there are so many features, the layer has been split into tiles of about 1 - 2 million points. Use the Tree Point Index polygon layer to identify which tiles you need to cover your area of interest. All tree point features are turned on by default, but restricted to a max of 1:10,000 scale for visibility. If you don't see tree points when you load this layer, zoom in further and wait a few seconds for the layer to render. To improve performance, turn off tree point tile layers you don't need. For detailed information on how this layer was derived, please see the History of Building- Vegetation Height, & Tree Canopy at King County storymap. For lidar intensity values, 0-120 = Deciduous, 120-200 = Conifer, 200-255 = Other. This is an estimated range. NDVI values range from -1 to 1, with values closer to 1 indicating lush green vegetation. Tree height is measured in feet above the bare earth DEM. A “tree” in this layer is any vegetation taller than 10 feet. No updates are planned for this layer.

本图层提供2021年金县（King County）树木中心点的近似清查数据。树木点位通过自动化流程生成，所用数据源包括2021年激光雷达（lidar）数据、Ecopia土地覆盖数据以及NAIP影像。本图层可估算树木位置与树高（基于激光雷达数据）、树木类型（常绿 vs 落叶，由激光雷达强度值判定），并通过影像结合归一化差异植被指数（NDVI）计算植被健康状况。本图层中的点位未经过质量保证/质量控制（QA/QC）处理，也未通过野外验证，其精度不及地面清查数据。不过金县境内现存树木约1.01亿株，因此本分析以极低的成本与人力投入，实现了树木点位与分布密度的可行近似估算。由于要素总量庞大，本图层已拆分为单幅包含100万至200万点位的瓦片。可通过树木点位索引（Tree Point Index）多边形图层，确定覆盖研究区域所需的瓦片范围。所有树木点位要素默认处于启用状态，但为保证可视化效果，显示比例尺上限设为1:10000。若加载图层后未显示树木点位，请进一步放大视图并等待数秒直至图层渲染完成。如需提升运行性能，请关闭非必要的树木点位瓦片图层。如需了解本图层生成的详细流程，请参阅《金县建筑、植被高度与树木树冠历史》故事地图（storymap）。激光雷达强度值判定规则如下：0-120对应落叶树，120-200对应针叶树，200-255对应其他植被，该范围为估算值。NDVI值的取值范围为-1至1，数值越接近1代表植被越繁茂翠绿。树木高度以裸土数字高程模型（DEM）之上的英尺数为单位计量。本图层中定义的"树木"指高度超过10英尺的所有植被。本图层暂无更新计划。