7500-FT Tiling Status for KC Raster Datasets

For more information about this layer please see the GIS Data Catalog. A spatial tiling index designed for storage of file-based image and other raster (i.e., LiDAR elevation, landcover) data sets. A regular grid with origin at 0,0 of the Washington North State Plane Coordinate System, with grid cells defined by orthogonal bounds 7500 feet long in easting and in northing. Only those cells currently involved in one of several image/raster data projects for King County and southwestern Snohomish County are labelled, though the labeling scheme can be extended. The name of the spatial index is derived from the acronym (I)n(D)e(X) (P)olygons at the (7500) foot tile level, or idxp7500. Cell label is a row-id cocantenated with a column-id generating a four-character identifier that uniquely identifies every cell. The row portion of the identifier is a two-character alpha code of the format aa, ab, ac.... ba, bb, etc. and the column portion is a two-digit integer value such as 01, 02, 03.... 11,12,13, etc. A composite cell identifier would be then, for example, aa01, aa02, .....ba11,ba12, etc. Not all image and raster data is stored at the tiling level represented by this index. Data is stored at this level if full-resolution, uncompressed data would generate larger than manageable file sizes at a larger tile size.有关此图层的更多详情，请参阅地理信息系统数据目录（GIS Data Catalog）。本空间分块索引专为基于文件的图像及其他栅格（即激光雷达（LiDAR）高程、土地覆盖）数据集的存储而设计。该索引采用以华盛顿州北州平面坐标系（Washington North State Plane Coordinate System）的(0,0)为原点的规则网格，网格单元的东向与北向正交边界长度均为7500英尺。目前仅为金县（King County）及斯诺霍米什县（Snohomish County）西南部的若干图像/栅格数据项目所涉及的单元进行了标注，不过该标注方案可进行扩展。该空间索引的名称源自缩写组合：(I)n(D)e(X) (P)olygons at the (7500) foot tile level，即idxp7500。单元标注由行标识符与列标识符拼接而成，可生成唯一标识每个网格单元的四字符标识符。其中标识符的行部分为格式遵循aa、ab、ac……ba、bb等规则的两位字母代码，列部分为格式如01、02、03……11、12、13等的两位整数值。例如，复合单元标识符可为aa01、aa02……ba11、ba12等。并非所有图像与栅格数据都存储于此索引所代表的分块层级。仅当全分辨率未压缩数据在更大分块尺寸下会生成超出可管理范围的文件大小时，数据才会存储于此层级。