50' Contour Lines - Santa Cruz County

This dataset represents 50 foot contour intervals for Santa Cruz County, Arizona. The data were created by processing hillshade TIF files derived from the U.S. Geological Survey National Elevation Dataset. The processing produced ESRI formatted coverages for each county or part of a county. The U.S. Geological Survey has developed a National Elevation Dataset (NED). The NED is a seamless mosaic of best-available elevation data. The 7.5-minute elevation data for the conterminous United States are the primary initial source data. In addition to the availability of complete 7.5-minute data, efficient processing methods were developed to filter production artifacts in the existing data, convert to the NAD83 datum, edge-match, and fill slivers of missing data at quadrangle seams. One of the effects of the NED processing steps is a much-improved base of elevation data for calculating slope and hydrologic derivatives. The specifications for the NED 1 arc second and 1/3 arc second data are - Geographic coordinate system, Horizontal datum of NAD83, except for AK which is NAD27, Vertical datum of NAVD88, except for AK which is NAVD29, Z units of meters.本数据集包含亚利桑那州圣克鲁斯县的50英尺等高距地形数据。 本数据集通过处理源自美国地质调查局国家高程数据集（U.S. Geological Survey National Elevation Dataset，简称NED）的地形晕渲TIFF文件生成，处理后为每个县或县辖区域生成了ESRI格式的Coverage数据集。 美国地质调查局构建的国家高程数据集（NED）是当前最优高程数据的无缝镶嵌集合，其中美国本土的7.5分比例尺高程数据为其核心初始源数据。 除完整覆盖7.5分比例尺数据外，研发团队还开发了高效处理流程，可用于过滤现有数据中的生产伪影、将坐标基准转换至北美大地基准面1983（NAD83）、执行边缘匹配，并填补地形图幅接缝处的缺失数据碎片。 该数据集的处理流程带来的一项显著成效，是为坡度与水文衍生参数的计算提供了大幅优化的高程数据基础。 NED 1角秒与1/3角秒数据的技术规范如下：采用地理坐标系，水平基准面为北美大地基准面1983（NAD83，阿拉斯加州除外，其水平基准面为北美大地基准面1927（NAD27））；垂直基准面为北美垂直基准面1988（NAVD88，阿拉斯加州除外，其垂直基准面为北美垂直基准面1929（NAVD29））；高程单位为米。