Digital Raster Graphic (DRG), Attu
- Originator: USGS
- Title: Digital
Raster Graphic (DRG), Attu
- The Digital Raster Graphic
(DRG) is a raster image of a
scanned USGS topographic map including the collar information,
georeferenced to the UTM grid.
- 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.
- 555443.804235, 5916212.151839
- "Ground Condition"
- Progress: Complete
digital raster graphic
- Department of Commerce,
1977, Countries, Dependencies, Areas of Special Sovereignty, and their Principal
Administrative Divisions (Federal Information Processing Standard 10-3):
Washington, Department of Commerce, National Institute of Standards and Technology.
- Department of Commerce,
1987, Codes for the Identification of the States, The District of Columbia
and the Outlying Areas Of The United States, and Associated Areas (Federal
Information Processing Standard 5-2): Washington, Department of Commerce,
National Institute of Standards and Technology.
- Acknowledgment of the USGS
would be appreciated in products derived from these data.
- Not Applicable.
- 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
- 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.
- 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
- Refer to the DRG collar
for information about vertical positional accuracy.
- Title: Attu
- The source map is scanned
to produce the DRG.
- The production procedures,
instrumentation, hardware, and software used in the collection of standard
DRG products vary depending on systems used at the contract, cooperator or
USGS production sites. The majority of DRG data sets are acquired through
government contract. The process step describes, in general, the process
used in the production of standard DRG data sets.
1. Production of a DRG begins
with the scanning of a paper 7.5-minute topographic map (map1) on a high-resolution
scanner. Scanning resolutions range from 500 - 1000 dpi with the output file
running between 160-300 mb.
2. Removal of screens (descreening)
and color quantization to reduce the number of colors also takes place during
the scanning phase.
3. The raw scan file is
then transformed and georeferenced using UTM coordinates of the sixteen 2.5-minute
grid ticks, which are obtained using the in-house produced program COORDAT
and stored in a ground control file. Those sixteen 2.5-minute ticks are
interactively visited and assigned their respective UTM coordinates. USGS
program XSHAPES4 then performs a piecewise linear rubber sheet transformation.
4. An output resolution
of 2.4 meters (8.2 feet) is chosen in order to resample the file to 250 dpi.
5. The image file is converted
to a TIFF and further reduced by converting the file to a run length encoding
Packbits compression(type 32773).
6. The color palette of
the compressed DRG is then standardized by replacing the original RGB values
assigned during the scanning process with standard RGB value combinations
using the in-house produced TIFFREMAP program.
7. Prior to archiving the
DRG undergoes the following quality assurance procedures:
a. The color index values
of each DRG are checked to ensure the RGB combinations are consistent with
the standardized color palette.
b. All DRG files are inspected
to ensure that they are geometrically consistent with normal map presentation.
c. Selected DRG's are checked
to ensure that data elements in the DRG metadata file correspond to the map
collar information and to the information in the associated image file.
d. Selected DRG's are checked
for georeferencing accuracy by comparing the book value of latitude and longitude
tick marks with corresponding tick intersections in the DRG image.
e. Transformations are checked
on selected DRG's by comparing the positions of well defined points, such
as UTM grid intersections in the graphic product, with the corresponding image
points in the DRG.
USGS DRG production specifications
are available on request from the National Mapping Division and Mid-Continent
Mapping Center by contacting:
Rolla-ESIC U.S. Geological
Survey 1400 Independence Rd., MS231 Rolla, MO 65401-2602 Phone (573)308-3500
Facsimile (573)308-3615 E-mail to firstname.lastname@example.org World Wide Web: http://mcmcweb.er.usgs.gov/drg/
Universal Transverse Mercator
row and column
North American Datum 1927
Each raster entity or pixel contains a color index from 0 through 12
referencing a color palette of RGB values from 0 through 255 in
which the standard colors used in the DRG are defined.
USGS DRG Color Palette
Digital Number Color Red Green Blue
0 Black 0 0 0
1 White 255 255 255
2 Blue 0 151 164
3 Red 203 0 23
4 Brown 131 66 37
5 Green 201 234 157
6 Purple 137 51 128
7 Yellow 255 234 0
8 Light Blue 167 226 226
9 Light Red 255 184 184
10 Light Purple 218 179 214
11 Light Grey 209 209 209
12 Light Brown 207 164 142
- Draft Standards for
Digital Raster Graphic.
- Earth Science Information
Center, U.S. Geological Survey Contact Address
- Address: 507 National
- City: Reston
- Postal_Code: 22092
1 800 USA MAPS
1 703 648 6045
- 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.
- Format_Name: TIFF
- Data General AViiON 6220 system running DG/UX version 5.4R3.10
- Offline_Media: "CD-ROM"
- "ISO 9660"; DRG image files with corresponding metadata
- For delivery on CD-ROM, the charge is $32 per CD-ROM
U.S. Geological Survey
590 National Center
- City: Reston
1 703 648 4533
- Copies of this
publication are available from anonymous File Transfer Protocol (anonymous
- "Content Standards for
Digital Geospatial Metadata"