Digital Raster Graphics (DRG), clipped 1:24,000 for Minnesota

This page last updated: 04/09/2007
Metadata created using Minnesota Geographic Metadata Guidelines


Metadata Summary

Originator U.S. Geological Survey and Minnesota DNR
Abstract A digital raster graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) topographic map. The original USGS scanned image includes all map collar information and is georeferenced to the UTM zone and datum of the printed quad map. The Minnesota Department of Natural Resources has removed the collar information to allow seamless viewing of adjacent DRGs. Where needed, DNR has also projected the files to UTM Zone 15 (extended across Minnesota), NAD83. The DRG can be used to collect, review, and revise other digital data, especially digital line graphs (DLG). When the DRG is combined with other digital products, such as digital orthophoto quadrangles (DOQ) or digital elevation models (DEM), the resulting image provides additional visual information for the extraction and revision of base cartographic information.
Browse Graphic View a sample of the data.
Time Period of Content Date
Currentness Reference Ground condition on the date of field checking or source aerial photographic materials as documented in the collar information on the printed USGS topographic map (to see the collar area, refer either to the printed topographic quad or to the original USGS DRG). Several dates appear on published USGS quads. The most prominent, and most widely referenced, is printed on the lower right corner of the map. This is usually the year the map was published or revised. In the smaller print along the bottom of the map are other dates for the year of field checking, year of photography, year of survey, or other dates for important work on the map. These dates can be same as the year of publication or up to several years earlier.
Access Constraints None
Use Constraints None. Acknowledgment of the U.S. Geological Survey and the Minnesota Department of Natural Resources would be appreciated in products derived from these data.

Redistribution Conditions: If obtaining these data from LMIC, it is understood that you and/or your organization have the right to use them for any internal purpose. If you modify them, you should document those changes in a metadata record that should accompany all redistributed data. If you transmit or provide these data in any form to another user, the data MUST be accompanied by a copy of LMIC's disclaimer NOTICE.TXT and all documentation provided with the original data set including the full metadata record.

If downloading the data from DNR's Data Deli, you will need to accept DNR's General Geographic Data License Agreement.
Distributor Organization Minnesota Land Management Information Center (LMIC)
Ordering Instructions 1. The clipped DRGs are distributed on the internet via the DNR Data Deli by clicking below after Online Linkage. Choose '24K DRGs Without Collars' from the list of available layers. Files are uniquely named: drgncimq####.tif ('####' is a quad code). Note: 1:100,000-scale and 1:250,000-scale DRGs are also available from this site.

2. A 5-CD set containing all of Minnesota's clipped DRGs is available from LMIC as Volume 3 of the Minnesota.data collection:
http://www.lmic.state.mn.us/chouse/mndata.html

(Note: Some off-site areas (small triangles of the original DRG collars) remain on the clipped DRGs. When displaying adjacent DRG files, these off-site areas will cover up information on adjoining DRGs. To correct this problem, set the off-site value (either 0 or 255) to 'transparent'.)

OTHER SOURCES: A number of the ORIGINAL USGS UNCLIPPED DRGs along the Mississippi River, including areas within Minnesota as well as Wisconsin, Iowa, Illinois and Missouri, are available online at no charge from the Upper Midwest Environmental Sciences Center website: http://www.umesc.usgs.gov/data_library/maps_quads_figs/drg.html

1:100,000-scale DRGs may be viewed at: http://terraserver.microsoft.com
Online Linkage Click here to download data. (See Ordering Instructions above for details.) By clicking here, you agree to the notice in "Distribution Liability" in Section 6 of this metadata.

Full Metadata

Digital Raster Graphics (DRG), clipped 1:24,000 for Minnesota

Go to Section:
1. Identification Information
2. Data Quality Information
3. Spatial Data Organization Information
4. Spatial Reference Information
5. Entity and Attribute Information
6. Distribution Information
7. Metadata Reference Information

 
Section 1 Identification Information   Top of page
Originator U.S. Geological Survey and Minnesota DNR
Title Digital Raster Graphics (DRG), clipped 1:24,000 for Minnesota
Abstract A digital raster graphic (DRG) is a scanned image of a U.S. Geological Survey (USGS) topographic map. The original USGS scanned image includes all map collar information and is georeferenced to the UTM zone and datum of the printed quad map. The Minnesota Department of Natural Resources has removed the collar information to allow seamless viewing of adjacent DRGs. Where needed, DNR has also projected the files to UTM Zone 15 (extended across Minnesota), NAD83. The DRG can be used to collect, review, and revise other digital data, especially digital line graphs (DLG). When the DRG is combined with other digital products, such as digital orthophoto quadrangles (DOQ) or digital elevation models (DEM), the resulting image provides additional visual information for the extraction and revision of base cartographic information.
Purpose The DRG is used for validating digital line graphs (DLGs) and for DLG data collection and revision. The DRG can help assess the completeness of digital data from other mapping agencies. It can also be used to produce hybrid products. These include combined DRGs and DOQs for revising and collecting digital data, DRGs and DEMs for creating shaded-relief DRGs, and combinations of DRG, DOQ, and DLG data. Although a standard DRG is an effective mapping tool, its full potential for digital production is realized in combination with other digital data.

Clipping the collar information allows seamless viewing of adjacent DRGs. Standardizing the UTM zone and the datum matches the data with many other statewide data sets available in Minnesota.
Time Period of Content Date
Currentness Reference Ground condition on the date of field checking or source aerial photographic materials as documented in the collar information on the printed USGS topographic map (to see the collar area, refer either to the printed topographic quad or to the original USGS DRG). Several dates appear on published USGS quads. The most prominent, and most widely referenced, is printed on the lower right corner of the map. This is usually the year the map was published or revised. In the smaller print along the bottom of the map are other dates for the year of field checking, year of photography, year of survey, or other dates for important work on the map. These dates can be same as the year of publication or up to several years earlier.
Progress Complete
Maintenance and Update Frequency Irregular
Spatial Extent of Data Minnesota
Bounding Coordinates -97.25
-89.50
49.50
43.50
Place Keywords Minnesota
Theme Keywords imageryBaseMapsEarthCover, digital raster graphic, DRG, topographic map
Theme Keyword Thesaurus ISO 19115 Topic Category
Access Constraints None
Use Constraints None. Acknowledgment of the U.S. Geological Survey and the Minnesota Department of Natural Resources would be appreciated in products derived from these data.

Redistribution Conditions: If obtaining these data from LMIC, it is understood that you and/or your organization have the right to use them for any internal purpose. If you modify them, you should document those changes in a metadata record that should accompany all redistributed data. If you transmit or provide these data in any form to another user, the data MUST be accompanied by a copy of LMIC's disclaimer NOTICE.TXT and all documentation provided with the original data set including the full metadata record.

If downloading the data from DNR's Data Deli, you will need to accept DNR's General Geographic Data License Agreement.
Contact Person Information Tim Loesch, GIS Application Specialist
Minnesota Department of Natural Resources, MIS
500 Lafayette Road
St. Paul, MN 55155
Phone: 651-296-0654
FAX: 651-297-4946
E-mail: tim.loesch@dnr.state.mn.us
Browse Graphic View a sample of the data.
Browse Graphic File Description
Associated Data Sets 1. USGS Digital Raster Graphics: 1:24,000-scale, original USGS version. Contains the collar information from the original USGS 1:24,000-scale topographic maps and matches the UTM zone and datum of the original maps. For more information, see http://www.lmic.state.mn.us/chouse/metadata/drg_24k.html or contact the USGS Earth Science Information Center at: esic@mcmcmail.er.usgs.gov or (573) 308-3500.

2. USGS Digital Raster Graphics: 1:100,000-scale

3. USGS Digital Raster Graphics: 1:250,000-scale

 
Section 2 Data Quality Information Top of full metadata Top of page
Attribute Accuracy The USGS DRG uses a standard palette to ensure uniform color throughout a particular map series. The RGB (red, green, blue) 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 DRGs within a series must have the same RGB value.

DRGs are examined to ensure color consistency within a series. Inspections are performed on selected DRGs to ensure that both the order of digital numbers and digital number values are correct. Colors will be checked for color compliance to map series and for major color differences between features on the DRG and similar features on the source map. Color consistency throughout each series is checked by comparing a DRG to its neighboring quadrangles whenever possible.
Logical Consistency 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 For original USGS DRGs: Image completeness is checked by visually inspecting a sampling of DRGs. 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.

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.
Horizontal Positional Accuracy A random sampling of DRGs will be accuracy tested. The accuracy test will be performed by comparing the positions of UTM grid intersections on the source graphic against the corresponding location on the digital image. A visual inspection will determine whether those coordinates fall within the pixels that define a grid tick.

DRGs will retain the horizontal accuracy of the source maps. Most USGS printed maps contain the National Map Accuracy Standards (NMAS) note in the collar area (to see the collar area, refer either to the printed topographic quad or to the original USGS DRG). The NMAS states that for maps on publication scales of 1:20,000 or smaller, not more than 10 percent of the points tested shall be in error by more than 1/50 inch measured on the publication scale. Test points must be 'well-defined', that is, easily visible or recoverable on the ground. For DRGs this accuracy statement applies only to that area of the DRG that falls within the neatline of the source map (excluding inset areas). Overedge areas falling outside the transformation boundary area (the map neatline), can exhibit anomalies or discrepancies. These anomalies also will appear in the map inset areas and in the map collar. For maps without the NMAS note, the horizontal accuracy is unknown. However, the DRG will retain the accuracy of the source map.
Vertical Positional Accuracy In the DRG, the vertical positional accuracy is referenced in the DRG collar (to see the collar area, refer either to the printed topographic quad or to the original USGS DRG).
Lineage Data Source:
The source for Minnesota DRGs are the standard 1:24,000-scale quadrangle format USGS topographic maps as described in the Federal Geographic Data Committee Manual of Federal Geographic Data Products. The standard area of coverage of a DRG is the entire area printed on a USGS standard series topographic map including the map collar, any overedge areas, and insets.

USGS Processing Steps:
Production of a DRG begins with the scanning of a paper 7.5-minute topographic map on a high-resolution scanner. Scanning resolutions range from 500-1,000 dpi with an output file of 160-300 MB in size. Removal of screens (descreening) and color quantization to reduce the number of colors also takes place during the scanning phase.

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.

An output resolution of 2.4 meters (8.2 feet) is chosen to resample the file to 250 dpi. 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).

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.

Prior to archiving, the DRG undergoes the following quality assurance procedures:

1. The color index values of each DRG are checked to ensure the RGB combinations are consistent with the standardized color palette.

2. All DRG files are inspected to ensure that they are geometrically consistent with normal map presentation.

3. 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.

4. 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.

5. 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 the U.S. Geological Survey (see Section 6 for Distributor Contact).

Minnesota DNR Processing Steps:
1. Imported the original USGS DRGs into EPPL7 raster format.
2. Shifted to NAD83 using the average x and y shift for NAD27 to NAD83 calculated for each section corner in the quad and applied to the header file.
3. Projected to UTM Zone 15 (extended across Minnesota) if necessary.
4. Removed the collar area by clipping with a NAD83 quadrangle boundary.
5. Exported from EPPL7 format to GeoTIFF format.
6. The few quads that had overedge areas or that were already NAD83 were processed individually.
Source Scale Denominator 24000
 
Section 3 Spatial Data Organization Information Top of full metadata Top of page
Native Data Set Environment
Geographic Reference for Tabular Data
Spatial Object Type Raster
Vendor Specific Object Types Cell
Tiling Scheme 7.5-minute quadrangle (1:24,000-scale)
 
Section 4 Spatial Reference Information Top of full metadata Top of page
Horizontal Coordinate Scheme UTM
Ellipsoid GRS80
Horizontal Datum NAD83
Horizontal Units Meters
Distance Resolution Unknown
Altitude Datum Not applicable
Altitude Units Not applicable
Depth Datum Not applicable
Depth Units Not applicable
UTM Zone Number 15E
Coordinate Offsets or Adjustments None
 
Section 5 Entity and Attribute Information Top of full metadata Top of page
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.

Digital Number, Color, Red Green Blue Values

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
Entity and Attribute Detailed Citation Standards for Digital Raster Graphics. Download documents from:
http://rmmcweb.cr.usgs.gov/public/nmpstds/drgstds.html
 
Section 6 Distribution Information Top of full metadata Top of page
Publisher Minnesota Department of Natural Resources
Publication Date 1998
Contact Person Information Nancy Rader
GIS Data Coordination Specialist
Minnesota Land Management Information Center (LMIC)
658 Cedar Street, Room 300
St. Paul, MN 55155
Phone: 651-201-2489
FAX: 651-296-3698
E-mail: clearing.house@state.mn.us
Distributor's Data Set Identifier drg24dnr - clipped DRG's
Distribution Liability Limitations: Although extensive effort has been made to produce error free and complete data, all geographic information has limitations due to the scale, resolution, date and interpretation of the original source materials. You should consult available data documentation (metadata) for these particular data to determine their limitations and the precision to which they depict distance, direction, location or other geographic characteristics. These data may be subject to periodic change without prior notification.

No Warranty: These data are provided as is, without any warranty whatsoever, including but not limited to any warranty as to their performance, merchantability, or fitness for any particular purpose.

Liability: The entire risk as to the results of the use of these data is assumed by the user. LMIC is not responsible for any interpretation or conclusions based on these data made by those who acquire or use it. LMIC shall not be liable for any direct, indirect, special, incidental, compensatory or consequential damages or third party claims resulting from the use of these data, even if LMIC has been advised of the possibility of such potential loss or damage. In States that do not allow the exclusion or limitation of incidental or consequential damages, you may not use these data.

Redistribution Conditions: In obtaining these data from LMIC, it is understood that you and/or your organization have the right to use them for any internal purpose. If you modify them, you should document those changes in a metadata record that should accompany all redistributed data. If you transmit or provide these data in any form to another user, the data MUST be accompanied by a copy of this disclaimer and all documentation provided with the original data set including the full metadata record.

Data Delivered on Electronic Media: If these data have been requested from LMIC on magnetic media, CD-ROM or any other physical media, LMIC will deliver this product in the computer-readable format agreed upon with the requestor. LMIC will re-issue these data if they are determined unreadable by correctly adjusted computer input devices, or when the medium is delivered in a damaged condition. Requests for re-issue of this digital data product must be made within 30 days of the date shipped from LMIC.
Transfer Format Name GeoTIFF
Transfer Format Version Number 6.0
Transfer Size Approximately 2 - 10 megabytes per file (unzipped).
Ordering Instructions 1. The clipped DRGs are distributed on the internet via the DNR Data Deli by clicking below after Online Linkage. Choose '24K DRGs Without Collars' from the list of available layers. Files are uniquely named: drgncimq####.tif ('####' is a quad code). Note: 1:100,000-scale and 1:250,000-scale DRGs are also available from this site.

2. A 5-CD set containing all of Minnesota's clipped DRGs is available from LMIC as Volume 3 of the Minnesota.data collection:
http://www.lmic.state.mn.us/chouse/mndata.html

(Note: Some off-site areas (small triangles of the original DRG collars) remain on the clipped DRGs. When displaying adjacent DRG files, these off-site areas will cover up information on adjoining DRGs. To correct this problem, set the off-site value (either 0 or 255) to 'transparent'.)

OTHER SOURCES: A number of the ORIGINAL USGS UNCLIPPED DRGs along the Mississippi River, including areas within Minnesota as well as Wisconsin, Iowa, Illinois and Missouri, are available online at no charge from the Upper Midwest Environmental Sciences Center website: http://www.umesc.usgs.gov/data_library/maps_quads_figs/drg.html

1:100,000-scale DRGs may be viewed at: http://terraserver.microsoft.com
Online Linkage Click here to download data. (See Ordering Instructions above for details.) By clicking here, you agree to the notice in "Distribution Liability" above.
 
Section 7 Metadata Reference Information Top of full metadata Top of page
Metadata Date 04/09/2007
Contact Person Information Nancy Rader, GIS Data Coordination Specialist
Minnesota Land Management Information Center (LMIC)
658 Cedar Street, Room 300
St. Paul, MN 55155
Phone: 651-201-2489
FAX: 651-296-3698
E-mail: clearing.house@state.mn.us
Metadata Standard Name Minnesota Geographic Metadata Guidelines
Metadata Standard Version 1.2
Metadata Standard Online Linkage http://www.lmic.state.mn.us/gc/stds/metadata.htm


This page last updated: 04/09/2007