50' Contour Lines - Pinal County

This dataset represents 50 foot contour intervals for Pinal 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.本数据集涵盖美国亚利桑那州（Arizona）皮纳尔县（Pinal County）的50英尺等高距数据。本数据集通过处理源自美国地质调查局（U.S. Geological Survey）国家高程数据集（National Elevation Dataset, NED）的晕渲TIF文件生成，该处理流程为各县级行政区或县内分区生成了ESRI格式的Coverage数据。 美国地质调查局现已构建国家高程数据集（NED），该数据集为最优可用高程数据的无缝镶嵌成果。美国本土48州的7.5弧分高程数据是其主要初始源数据。除提供完整的7.5弧分数据外，研发团队还开发了高效处理方法，用于过滤现有数据中的生产伪影、将数据转换至NAD83基准面、执行边缘匹配，并填补图幅接缝处的缺失狭长条带数据。 国家高程数据集的处理流程带来的一项核心优势，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弧秒与1/3弧秒数据的规格如下：地理坐标系采用NAD83水平基准面（阿拉斯加州，简称AK除外，其采用NAD27基准面），垂直基准面为NAVD88（AK除外，其采用NAVD29基准面），Z轴单位为米。