What are DRGs
The USGS Standard Digital Raster Graphis
are scanned images of USGS topographic maps, including all map
collar information. The image inside the map neatline is georeferenced
to the surface of the earth and fit to the Universal Transverse
Mercator projection. The horizontal positional accuracy and datum
of the DRG matches the accuracy and datum of the source map.
The map is scanned at a minimum resolution of 250 dots per inch.
Uses for DRG
DRGs can be used as background images and basemaps in any GIS, GPS and graphic software able to display TIFF images. GIS and GPS software supporting GeoTiff format will be able to georeference map images.
Distribution of DRG
Gecko Software distributes the USGS DRGs by 1° blocks. Typical block contains 64 71/2 minute quads (1;24,000 scale), two 60x30 minute quads (1;100,000 scale) and one 1°x2° quad (1;250,000 scale).
Why Order From Gecko Software
- Gecko Software has DRG coverage for the entire US.
- Orders will be sent within 3 working days. Compared to 5-6 weeks from the USGS.
- $25.00 per 1° Block
- Friendly sales and support staff to aid the customer in locating and obtaining DRGS.
Specifications:
- High resolution scanned image, (min. 250 dpi).
- Each image is corrected using 16 control points.
- 4 bit 14 color images.
- GeoTiff format including.
Tiff World Files and metadata.
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