Digital Raster Graphics (DRG) data is a scanned image of a USGS topographic map. These digital maps are available for free on the Internet or are sold commercially in collections on CDs or DVDs.
These digital maps are scanned at 250 dpi (dots per inch) and stored in a TIFF file format, using embedded GeoTIFF (geographic information) tags for location data.
You can view the map by itself or both the map and its location data. Use one of the following methods:
These digital maps are scanned at 250 dpi (dots per inch) and stored in a TIFF file format, using embedded GeoTIFF (geographic information) tags for location data.
You can view the map by itself or both the map and its location data. Use one of the following methods:
- View the map by opening the DRG file with any current graphics program that supports large TIFF files.
- Use the DRG file with a mapping program that supports GeoTIFF to view the map and access its location data.
For more technical details about USGS digital map data, check out the agency’s product Web site:
mapping.usgs.gov/products.html
mapping.usgs.gov/products.html
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