Digital Raster Graphics

A digital raster graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) topographic map. The scanned image includes all map collar information. The image inside the map neatline is georeferenced to the surface of the Earth. The DRG can be used to collect, review, and revise other digital data especially digital line graphs (DLG). When the DRG is combined with other digital products, such as digital orthophoto quadrangles (DOQ) or digital elevation models (DEM), the resulting image provides additional visual information for the extraction and revision of base cartographic information. The USGS is producing DRGs of the 1:24,000-, 1:25,000-, 1:63,360- (Alaska), 1:100,000-, and 1:250,000-scale topographic map series.

数字栅格图（digital raster graphic, DRG）是美国地质调查局（U.S. Geological Survey, USGS）地形图的扫描影像。该扫描影像包含全部图廓整饰信息，内图廓线范围内的影像已完成地球表面地理配准。DRG可用于采集、审查及修订其他数字数据，尤其适用于数字线划图（digital line graphs, DLG）的相关作业。当DRG与数字正射影像图幅（digital orthophoto quadrangles, DOQ）、数字高程模型（digital elevation models, DEM）等其他数字产品结合使用时，所生成的复合影像可为基础制图信息的提取与修订提供额外的视觉辅助信息。目前美国地质调查局正生产1:24000、1:25000、1:63360（阿拉斯加地区专用）、1:100000及1:250000比例尺的地形图系列数字栅格图。