U.S. Geological Survey 20021024 map Helena, MT Montana State Library http://geoinfo.msl.mt.gov/data/DRG/MrSID http://mslapps.mt.gov/Geographic_Information/Data/DataList/datalist_Details.aspx?did={1C37C4AF-9EF2-42F4-B790-E884CD8285DF} 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. 1950 1996 Publication Date Complete -116.57 -103.45 49.08 43.76 ISO 19115 Topic Category imageryBaseMapsEarthCover digital raster graphic DRG topographic map Montana Wyoming Idaho None 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. Montana State Library mailing address

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Helena Montana 59620-1800 406-444-5354 Montana Relay 711 406-444-0266 geoinfo@mt.gov http://docs.msl.mt.gov/geoinfo/Images/Metadata/drg.gif Most DRGs in Montana were produced through and Innovative Partnership agreement between the Land Information Technology Company, Ltd., of Aurora, CO and the USGS. 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. 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. Approximate horizontal accuracy is 40 feet, or 12 meters, assuming that the original map meets National Map Accuracy Standards. 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. National Mapping Division U.S. Geological Survey 1940 map Reston, VA U.S. Geological Survey 24000 paper 1940 1996 Publication Date D7.5 The data files are images of these maps. See individual image metadata files for the map dates. 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/ D7.5 1996 usgs 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. usgs 20000920 fin 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. usgs 20021023 fin Raster Pixel 22970 33630 State Plane Coordinate System 1983 2500 45 49 -109.5 44.25 600000 0 row and column 2.4384 2.4384 meters North American Datum of 1983 Geodetic Reference System 80 6378137.0 298.257 NGVD29 20 FEET Images of contours 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 Draft Standards for Digital Raster Graphic. Montana State Library mailing address

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Helena MT 59620-1800 406-444-5354 Montana Relay 711 406-444-0266 geoinfo@mt.gov Downloadable Data 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. MrSID http://geoinfo.msl.mt.gov/data/DRG/MrSID 20160823 20021024 Montana State Library mailing address

PO Box 201800

Helena Montana 59620-1800 406-444-5354 Montana Relay 711 406-444-0266 geoinfo@mt.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 {CBCC7502-242B-495D-A7DF-C6C4BB046948}