Digital raster graphic(DRG) and digital line graphic(DLG) are two digital maps that can be taken cheaply, and DLG is a commonest data format now, it is the main data source of GIS.

• 数字栅格图和数字线划图是可以低成本获取的两种数字地图,而DLG是目前最普遍的矢量数据格式,是GIS的主要数据来源。