USGS, 19970610, USGS Digital Raster Graphic 1:250,000 and 1:63,360 Quadrangles: USGS, Reston, VA.
This is a Raster data set. It contains the following raster data types:
The map projection used is Albers Conical Equal Area.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest 0.000100
Ordinates (y-coordinates) are specified to the nearest 0.000100
Planar coordinates are specified in meters
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257222.
This DRG was produced through an Innovative Partnership agreement between The Land Information Technology Company, Ltd., of Aurora, CO and the USGS.
A DRG is useful as a source or background layer in a GIS, as a means to perform quality assurance on other digital products, and as a source for the collection and revision of DLG data. DRG's can also be merged with other digital data, e.g. DEM's or DOQ's, to produce a hybrid digital file.
USGS, 1985, Portair SW: USGS, Reston, VA.
Data sources used in this process:
The DRG is an 8-bit color image that employs a color palette to ensure uniform colors throughout a particular DRG series. All DRG's within a series must have the same RGB value.
While the datum of the published map is retained to be consistent with other USGS digital data, this image is cast on the UTM and may be INCONSISTENT with the credit note on the image collar.
Refer to the DRG collar for information about vertical positional accuracy.
The DRG is a faithfully reproduced digital image of the original source map. Some differences may be detected between the source graphic used and the DRG due to the RGB values assigned that particular color. The intent is to recreate those colors as near as possible. Data completeness for DRG files reflect content of the source graphic. Features may have been eliminated or generalized on the source graphic due to scale and legibility constraints. For information on collection and inclusion criteria, see U.S. Geological Survey, 1994, Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle Maps: National Mapping Program Technical Instructions and U.S. Geological Survey, 1994, Standards for Digital Line Graphs: National Mapping Program Technical Instructions.
Are there legal restrictions on access or use of the data?
- Access_Constraints: "None"
- Acknowledgment of the USGS would be appreciated in products derived from these data.
1 800 USA MAPS (voice)
Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty. The USGS will warrant the delivery of this product in computer-readable format and will offer appropriate adjustment of credit when the product is determined unreadable by correctly adjusted computer input peripherals, or when the physical medium is delivered in damaged condition. Requests for adjustment of credit must be made within 90 days from the date of this shipment from the ordering site.
|Data format:||TIFF (version 6.0)|
|Media you can order:||
(format "ISO 9660"; DRG image files with corresponding metadata files.)
1 703 648 4533 (voice)
Copies of this publication are available from anonymous File Transfer Protocol (anonymous FTP); <ftp://fgdc.er.usgs.gov/>