Gridded Population of the World, Version 4 (GPWv4): National Identifier Grid, Revision 11

The Gridded Population of the World, Version 4 (GPWv4): National Identifier Grid, Revision 11 is a raster representation of nation-states in GPWv4 for use in aggregating population data. This data set was produced from the input census units which were used to create a raster surface where pixels that cover the same census data source (most often a country or territory) have the same value. Note that these data are not official representations of country boundaries; rather, they represent the area covered by the input data. In cases where multiple countries overlapped a given pixel (e.g. on national borders), the pixels were assigned the country code of the input data set which made up the majority of the land area. The data file was produced as a global raster at 30 arc-second (~1 km at the equator) resolution. To enable faster global processing, and in support of research communities, the 30 arc-second data were aggregated to 2.5 arc-minute, 15 arc-minute, 30 arc-minute and 1 degree resolutions. Each level of aggregation results in the loss of one or more countries with areas smaller than the cell size of the final raster. Rasters of all resolutions were also converted to polygon shapefiles.
To provide a raster representation of nation-states in GPWv4 for use in aggregating population data.

世界栅格人口第四版（Gridded Population of the World Version 4，GPWv4）：国家标识网格修订版11，是GPWv4中用于人口数据聚合的主权国家栅格表征数据集。本数据集依托输入的普查单元数据生成，通过构建栅格表面，使覆盖同一普查数据源（多为国家或地区）的像素具有统一的像素值。需注意，此类数据并非官方的国家边界表述，仅代表输入数据所覆盖的区域范围。当多个主权国家的范围重叠于某一像素（例如国界线区域）时，该像素将被分配为占该像素陆地面积多数的输入数据集所属主权国家的国家代码。本数据文件为全球栅格数据，分辨率为30弧秒（赤道处约合1公里）。为提升全球数据处理效率并服务科研社区，30弧秒分辨率的数据被聚合为2.5弧分、15弧分、30弧分及1度四种分辨率。每一级聚合操作都会导致面积小于最终栅格单元尺寸的一个或多个主权国家丢失相关信息。所有分辨率的栅格数据均已转换为多边形形状文件（shapefile）。
用于GPWv4中人口数据聚合的主权国家栅格表征。