Metadata for Montana 1:24,000 scale DRG Quadrangles, MrSID version Metadata for Montana 1:24,000 scale DRG Quadrangles, MrSID version

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Identification Information:

Citation:

Originator: U.S. Geological Survey

Publication date: 10/24/2002

Title: Montana 1:24,000 scale DRG Quadrangles, MrSID version

Publication place: Helena, MT
Publisher: Montana State Library

Online linkage: http://geoinfo.msl.mt.gov/data/DRG/MrSID

Larger Work Citation:

Title: USGS Topographic Map Quadrangles of Montana, pre-1998
Online linkage: http://mslapps.mt.gov/Geographic_Information/Data/DataList/datalist_Details.aspx?did={1C37C4AF-9EF2-42F4-B790-E884CD8285DF}

Browse graphic file name: http://docs.msl.mt.gov/geoinfo/Images/Metadata/drg.gif

Abstract:

U.S. Geological Survey (USGS) Digital Raster Graphics (DRGs) are scanned, georeferenced images of USGS topographic maps.

These files are 1:24,000 scale DRG images that have been projected to Montana State Plane Coordinates. Their collars have been removed, they have been combined into rectangular blocks that are mostly about 50 miles wide and 35 miles high, and they have been compressed with MrSID. MrSID images may be viewed with free software available at http://www.lizardtech.com.

We received these map images in 1998. The files have not been updated since that time, and many of the maps are more than 50 years old. Newer versions of many of these images may be available for free download at the USGS Store. A shapefile index of the map dates is available at https://ftpgeoinfo.msl.mt.gov/Data/Spatial/NonMSDI/Raster/TopoQuads1998/24k/DRG_24k_Index.zip.

Time period of content:

Beginning date: 1950
Ending date: 1996
Currentness reference: Publication Date

Status:

Progress: Complete

Access constraints: None

Use constraints:

The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time.

Point of contact:

Montana State Library
PO Box 201800
Helena, Montana 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: Montana Relay 711
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov

Data set credit:

Most DRGs in Montana were produced through and Innovative Partnership agreement between the Land Information Technology Company, Ltd., of Aurora, CO and the USGS.

Data Quality Information:

Attribute accuracy report:

A DRG is an 8-bit color image that employs a color pallette to ensure uniform colors throughout a particular DRG series. All DRG's within a series must have the same RGB value. The MrSID compression algorithm has removed the color pallettes and converted the images to 24-bit color.

Completeness report:

DRGs are faithfully reproduced digital images of the original source maps. Some differences may be detected between the source graphics used and the DRGs due to the RGB values assigned that particular color. The intent is to re-create those colors as near as possible. Data completeness for DRG files reflect content of the source graphics. Features may have been eliminated or generalized on the source graphics 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.

Horizontal Positional Accuracy Report:

Approximate horizontal accuracy is 40 feet, or 12 meters, assuming that the original map meets National Map Accuracy Standards.

Vertical positional accuracy report:

Approximate horizontal accuracy of contours is one-half the contour interval of the map, assuming that the original map meets National Map Accuracy Standards. Elevations of benchmarks shown on the maps should be accurate to the nearest foot.

Lineage:

Source information:

Originator:: National Mapping Division
U.S. Geological Survey
Publication date: 1940
Title: 1:24,000-scale 7.5 minute quadrangles
Source scale denominator: 24000
Type of source media: paper
Source contribution:: The data files are images of these maps. See individual image metadata files for the map dates.
Beginning date: 1940
Ending date: 1996

Process step:

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 mcmcesic@usgs.gov
World Wide Web: http://mcmcweb.er.usgs.gov/drg/


Process date: 1996

Process step:

USGS DRG files were projected to Montana State Plane coordinates and converted to NAD83 using the Arc/Info GRIDWARP command, based on the projected coordinates of 45 evenly spaced points within the image. The margins were clipped from the images using 80 evenly spaced latitude/longitude coordinates along the neatline.


Process date: 09/20/2000

Process step:

Build a grid of 111 rectangles covering the DRG holdings of the State Library. Merge the DRG images within each rectangle and clip them to the rectangle boundaries. Compress the merged image with MrSID.


Process date: 10/23/2002

Spatial Data Organization Information:

Raster object information:

Raster object type: Pixel
Row count: 22970
Column count: 33630

Spatial Reference Information:

Horizontal coordinate system definition:

Grid coordinate system name: State Plane Coordinate System 1983

SPCS zone identifier: 2500

Lambert conformal conic:

Standard parallel: 45
Standard parallel: 49
Longitude of central meridian: -109.5
Latitude of projection origin: 44.25
False easting: 600000
False northing: 0

Planar distance units: meters

Geodetic model:

Horizontal datum name: North American Datum of 1983
Ellipsoid name: Geodetic Reference System 80
Semi-major axis: 6378137.0
Denominator of flattening ratio: 298.257

Altitude system definition:

Altitude datum name: NGVD29
Altitude resolution: 20
Altitude distance units: FEET
Altitude encoding method: Images of contours

Entity and Attribute Information:

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 the standard colors used in the DRG are defined.

USGS DRG Color Palette
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
Entity and attribute detail citation: Draft Standards for Digital Raster Graphic.

Distribution Information:

Distributor:

Montana State Library
PO Box 201800
Helena, MT 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: Montana Relay 711
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov

Resource description: Downloadable Data

Distribution liability:

Standard order process:

Digital form:

Metadata Reference Information:

Metadata date: 08/23/2016

Metadata review date: 10/24/2002

Metadata contact:

Montana State Library
PO Box 201800
Helena, Montana 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: Montana Relay 711
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov