A DRG is a scanned image of a USGS topographic map. The scanned
images distributed through GRANIT include only the map body, and
exclude any of the map collar information printed on the paper
quads. (For those interested in the complete map as printed,
they may be acquired from USGS (<URL:http://edcwww.cr.usgs.gov/webglis>.)
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, such as DLG data. When the DRG is combined with other
digital products, such as DOQ or DEM, the resulting image provides
additional visual information for the extraction and revision of base
cartographic information.
Purpose:
Because the DRG's are georeferenced to the surface of the Earth, they
mey be readily used as a layer in a geographic information system.
They are commonly used as background layers, and as a means to perform
quality assurance on other digital products. The DRGs can also be
merged with other digital data (e.g. digital elevation models or
digital orhophotoquads) to produce a hybrid digital file.
Supplemental_Information: Data distribution tile: 7.5-minute quadrangle.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1967
Currentness_Reference: Ground Condition
Status:
Progress: In work
Maintenance_and_Update_Frequency: Irregular
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -71.875
East_Bounding_Coordinate: -71.750
North_Bounding_Coordinate: 44.500
South_Bounding_Coordinate: 44.375
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: DRG
Theme_Keyword: Digital Raster Graphic
Theme_Keyword: Topographic Map
Theme_Keyword: Contour Line
Theme_Keyword: Digital Contours
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: United States
Place_Keyword: Northeast
Place_Keyword: New England
Place_Keyword: New Hampshire
Place_Keyword: MILES POND, VT-NH
Access_Constraints:
Acknowledgement of GRANIT and the US Geological Survey would
be appreciated in products derived from these data.
Use_Constraints: Not for legal use.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Complex Systems Research Center
The DRG is an 8-bit color image which employs a color palette
to ensure uniform colors throughout a particular DRG series.
The values for a particular color, therefore, will remain
consistent throughout that DRG series. Although the color
values of the DRG may sometimes match those of the paper
source map, a user will usually notice small differences
between the colors on the digital image and on the paper
map. Also, the quality of the user's output device
(e.g. monitor or printer) affects the
DRG color displayed.
Logical_Consistency_Report: Not Applicable
Completeness_Report:
The Digital Raster Graphic (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 digital raster
graphic 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/inclusion criteria, see USGS National Mapping Division
Product Standards for DLG and Quadrangle Maps, published as the
Technical Instructions.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Refer to the published map series for information about
horizontal positional accuracy. However, note that the
GRANIT image is re-cast onto the NH State Plane coordinate
system.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
Refer to the published map series for information about
vertical positional accuracy. However, note that the
GRANIT image is re-cast onto the NH State Plane coordinate
system.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator:
US Geological Survey or another mapping agency in
cooperation with USGS
The source map is scanned to produce the
Digital Raster Graphic.
Process_Step:
Process_Description:
The source DRG files were reprocessed to
conform to GRANIT database standards. Key
elements of the processing included:
- reprojecting the spatial data from
UTM meters (Zone 18/19), NAD27 to
NH State Plane feet, Zone 4676,
NAD83.
- clipping out the map body from the
full image (to allow for mosaicing
of adjacent quadrangles)
The specific steps applied to each data file
included the following:
1. Data for each quad was retrieved from the USGS as a
tif image (with associated tfw, or tif world file)
2. In Arc/Info:
a. Convert the TIFFs to GRIDS (using IMAGEGRID)
b. Reproject the GRID to NH State Plane feet, NAD83
c. Clip out only the map body using the GRANIT
7.5-minute quadrangle overlay coverage
d. Run GRIDIMAGE to convert the GRID back into
a tiff format
e. MrSIDs - Convert TIFF image to geo-referenced
MrSID with 1:20 encoding ratio
Source_Used_Citation_Abbreviation: DRG-2
Process_Date: 19980321
Source_Produced_Citation_Abbreviation: Version 1
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Organization: Complex Systems Research Center
Contact_Person: GRANIT Database Manager
Contact_Position: GRANIT Database Manager
Contact_Address:
Address_Type: mailing and physical address
Address: Morse Hall, University of New Hampshire
City: Durham
State_or_Province: NH
Postal_Code: 03824
Country: US
Contact_Voice_Telephone: 603-862-1792
Contact_Facsimile_Telephone: 603-862-0188
Contact_Electronic_Mail_Address: granit@unh.edu
Hours_of_Service: 8:30AM-5PM, EST
Process_Step:
Process_Description:
All preliminary process steps were performed
by USGS in the development of the source DRG's,
as described below.
The production procedures, instrumentation, hardware and
software used in the collection of standard U.S. Geological
Survey (USGS) Digital Raster Graphic (DRG) products vary
depending on systems used at the contract, cooperator or
National Mapping Division (NMD) production sites. The
majority of DRG datasets are acquired through government
contract. The process step below describes, in general, the
process used in the production of standard USGS DRG
datasets.
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. An output resolution of 2.4 meters (7.9 feet) is chosen
in order to resample the file to 250 dots per inch (dpi).
3. 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.
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 to 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 to the
corresponding image points in the DRG.
Source_Used_Citation_Abbreviation: MAP-1
Process_Date: unknown
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Pixel
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: State Plane Coordinate System 1983
State_Plane_Coordinate_System:
SPCS_Zone_Identifier: New Hampshire
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.999967
Longitude_of_Central_Meridian: -71.666667
Latitude_of_Projection_Origin: 42.500000
False_Easting: 984249.999900
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: Row and column
Coordinate_Representation:
Abscissa_Resolution: 2.4
Ordinate_Resolution: 2.4
Planar_Distance_Units: feet
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: GRS 80
Semi-major_Axis: 20925604.4720406
Denominator_of_Flattening_Ratio: 298.26
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
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 standard colors
used in the DRG are defined. Value 15 is reserved
for "no data".
COLOR
INDEX COLOR R G B
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 Light 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 Gray 209 209 209
12 Light Brown 207 164 142
15 "No Data"
For those using these files in ArcView or ArcGIS, set color
15 to "no color".
Entity_and_Attribute_Detail_Citation:
See Draft Standards for Digital Raster Graphic from USGS.
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Complex Systems Research Center
Contact_Person: GRANIT Database Manager
Contact_Position: GRANIT Database Manager
Contact_Address:
Address_Type: mailing and physical address
Address: Morse Hall, University of New Hampshire
City: Durham
State_or_Province: NH
Postal_Code: 03824
Country: US
Contact_Voice_Telephone: 603-862-1792
Contact_Facsimile_Telephone: 603-862-0188
Contact_Electronic_Mail_Address: granit@unh.edu
Hours_of_Service: 8:30AM-5PM, EST
Resource_Description: DRG034 - Digital Raster Graphic for Quad 034
Distribution_Liability:
Digital data in NH GRANIT represent the efforts of the
contributing agencies to record information from the cited
source materials. Complex Systems Research Center, under
contract to the NH Office of State Planning, and in
consultation with cooperating agencies, maintains a
continuing program to identify and correct errors in these
data. OSP, CSRC, and the cooperating agencies make no claim
as to the validity or reliability or to any implied uses of
these data.
