1:24,000 - 7.5 minute Digital Raster Graphics for the District of Columbia


Identification_Information:
Citation:
Citation_Information:
Originator:U.S. Geological Survey
Publication_Date:1996
Title:
1:24,000 - 7.5 minute Digital Raster Graphics for the District of Columbia
Publication_Information:
Publication_Place:Reston, Virginia
Publisher:U.S. Geological Survey
Online_Linkage: http://www.pasda.psu.edu/
Larger_Work_Citation:
Citation_Information:
Originator:U.S. Geological Survey
Publication_Date:Unknown
Title:
Digital Raster Graphic
Publication_Information:
Publication_Place:Reston, Virginia
Publisher:U.S. Geological Survey
Other_Citation_Details:
none
Online_Linkage: http://www.usgs.gov
Description:
Abstract:
A Digital Raster Graphic (DRG) is a raster image of a scanned USGS 
topographic or planimetric map including the collar information, georeferenced to 
the UTM grid.
Purpose:
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 vector data. DRGs can also be merged with other digital data, for example, DEMs or DOQs to produce a hybrid digital file.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date:unknown
Currentness_Reference:
ground condition
Status:
Progress:Complete
Maintenance_and_Update_Frequency:Irregular
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate:-77
East_Bounding_Coordinate:-76.875
North_Bounding_Coordinate:38.875
South_Bounding_Coordinate:38.75
Keywords:
Theme:
Theme_Keyword_Thesaurus:ISO 19115 Topic Categories
Theme_Keyword:digital raster graphic
Theme_Keyword:drg
Theme_Keyword:topographic quadrangle
Theme_Keyword:topographic map
Theme_Keyword:raster image
Theme_Keyword:imageryBaseMapsEarthCover
Place:
Place_Keyword:District of Columbia
Access_Constraints:none
Use_Constraints:
Acknowledgment of the USGS would be appreciated in products derived 
from these data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:U.S. Geological Survey
Contact_Address:
Address_Type:mailing address
Address:
508 National Center
City:Reston
State_or_Province:VA
Postal_Code:22092
Contact_Voice_Telephone:1-800-USA-MAPS
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
The DRG uses a standard palette to ensure uniform color throughout a particular map series. The RGB 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 monitor affects the DRG color displayed. Although the DRG generally contains the complete content of the source map, features may occasionally be blurred because of substandard source materials. The DRG also may contain misclassified pixels (color noise). 
													 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.
Logical_Consistency_Report:
The USGS DRG is produced with the intention of replicating as close as possible the original source map. Users of the DRG will note, however, that a certain amount of "noise" can be discerned when small areas are blown up or viewed under zoomed-in conditions. This noise is in the form of random specks or pixels of color and halos due to any number of factors, such as, the quality of the source, the use of screens and patterns on the litho, and the unevenness of ink due to saturation and absorption. Discontinuities or breaks in linear features may also be present and are due to improper calibration or usage of the scanner, the condition of the source, and resampling.  Descreening, quantizing, and noise filtering are methods used to reduce noise, which, besides creating a more aesthetically pleasing image, have the added benefit of reducing the size of the image file. Removal of lithographic screen patterns is preferred but not required.
Completeness_Report:
Image completeness is checked by visually inspecting a sampling of DRG's. Each selected DRG will be examined for gaps (missing data) in the main body of the map, the map collar, the overedge areas, and any insets 
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Vertical_Positional_Accuracy:
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator:U.S. Geological Survey
Publication_Date:Unknown
Title:
7.5 Minute Series Topographic Quadrangles
Geospatial_Data_Presentation_Form:map
Publication_Information:
Publication_Place:Reston, VA
Publisher:U.S. Geological Survey
Source_Scale_Denominator:24,000
Type_of_Source_Media:paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date:unknown
Source_Currentness_Reference:
ground condition
Source_Citation_Abbreviation:
map1
Source_Contribution:
The source map is scanned to produce the DRG
Process_Step:
Process_Description:
The production procedures, instrumentation, harware and software used in the 
collection of standard DRG products vary depending on systems used at the 
contract, cooperator, or the USGS production sites.  The majority of DRG data sets 
are acquired through government partnership and contract.  The process step 
describes, in general, the process used in the production of DRGs from 
1:24,000-scale maps.
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 500-1,000 dpi with an output file of 160-300 Mb in size.
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. The USGS program XSHAPES4 then performs a piecewise linear rubber 
sheet transformation.
4. An output resolution of 2.4 meters (8.2 feet) is chosen to resample the file to 
250 dpi.
5.  The image file is converted to a TIFF 6.0 image and further reduced by 
converting the file to a run length encoded 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-houseproduced TIFFREMAP program.
7. The DRG metadata file is completed.
8.  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 General Cartographic Transformation Package
(GCTP) calculated 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.
Process_Date:1997
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method:Raster
Raster_Object_Information:
Raster_Object_Type:Pixel
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name:Universal Transverse Mercator
Universal_Transverse_Mercator:
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method:row and column
Coordinate_Representation:
Abscissa_Resolution:25.40000078
Ordinate_Resolution:25.40000078
Planar_Distance_Units:meters
Geodetic_Model:
Horizontal_Datum_Name:North American Datum of 1927
Ellipsoid_Name:Clarke 1866
Semi-major_Axis:6378206.4
Denominator_of_Flattening_Ratio:294.98
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Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Each raster entity or pixel contains a digital number 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. 
Entity_and_Attribute_Detail_Citation:
Standards for Digital Raster Graphic
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Penn State Institutes of the Environment
Contact_Address:
Address_Type:mailing and physical address
Address:
115 Land and Water Building
City:University Park
State_or_Province:PA
Postal_Code:16802
Country:United States
Contact_Voice_Telephone:(814) 865 - 8792
Contact_Electronic_Mail_Address:pasda@psu.edu
Distribution_Liability:
The USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name:Tagged Image File Format (TIFF)
Format_Version_Number:6.0
File_Decompression_Technique:zip
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:U.S. Geological Survey EROS Data Center
Contact_Position:Customer Services Representative
Contact_Address:
Address_Type:mailing and physical address
Address:
Customer Services U.S. Geological Survey EROS Data Center
City:Sioux Falls
State_or_Province:SD
Postal_Code:57198
Country:USA
Contact_Voice_Telephone:605-594-6151
Contact_TDD/TTY_Telephone:605-594-6933
Contact_Facsimile_Telephone:605-594-6589
Contact_Electronic_Mail_Address:custserv@edcmail.cr.usgs.gov
Hours_of_Service:7:30 am to 4:00 pm CT
Contact Instructions:
Automated Ordering. Your order is forwarded to Customer Services at the U.S. Geological Survey's EROS Data Center. A Customer Services Representative contacts you to discuss your order and your mode of payment. 

Manual Ordering. Write down the ordering ID(s) for your item(s). Contact Customer Services.
Distribution_Liability:
Although these data have been processed successfully on a computer system at the USGS, no warrenty 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 of the shipment from the 
ordering site.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name:TIFF
Format_Version_Number:6.0
Format_Version_Date:Unknown
Digital_Transfer_Option:
Fees: From USGS: $32 for each cd-rom. FTP from http://www.pasda.psu.edu free of charge
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Metadata_Reference_Information:
Metadata_Date:19961125
Metadata_Review_Date:19990726
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:Penn State Institutes of the Environment
Contact_Address:
Address_Type:mailing address
Address:
115 Land and Water building
City:University Park
State_or_Province:Pennsylvania
Postal_Code:16802
Country:United States
Contact_Voice_Telephone:(814) 865 - 8792
Contact_Electronic_Mail_Address:pasda@psu.edu
Metadata_Standard_Name:Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version:FGDC-STD-001-1998
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