Digital Raster Graphic (DRG) Image Service for Idaho

Digital Raster Graphic (DRG) Image Service for Idaho

Frequently-asked questions:

What does this data set describe?

Title:
Digital Raster Graphic (DRG) Image Service for Idaho

Abstract: 
This image service includes USGS digital raster graphics (DRG) for Idaho which are displayed as a seamless raster mosaic. Vector layers representing USGS quadrangle boundaries contain the quadrangle name of each DRG in the raster mosaic. 

The Digital Raster Graphic (DRG) is a raster image of a scanned USGS topographic map.

  1. How should this data set be cited?

    Idaho Geospatial Data Clearinghouse, U.S. Geological Survey (USGS), 2002, Digital Raster Graphic (DRG) Image Service for Idaho: Idaho Geospatial Data Clearinghouse, Moscow, ID USA.

    Online links:
  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -119.229997
    East: -109.241644
    North: 49.257188
    South: 40.693165

  3. What does it look like?

    Thumbnail image:

  4. Does the data set describe conditions during a particular time period?

    Calendar date: unknown
    Currentness reference: 
    ground condition

  5. What is the general form of this data set?

    Geospatial data presentation form: raster digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set.

    2. What coordinate system is used to represent geographic features?

      The map projection used is Transverse Mercator.

      Projection parameters:
      Transverse Mercator
      Scale factor at central meridian: 0.999600
      Longitude of central meridian: -114.000000
      Latitude of projection origin: 42.000000
      False easting: 500000.000000
      False northing: 100000.000000

      Planar coordinates are encoded using coordinate pair.
      Planar coordinates are specified in meters.

      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.400000.
      The flattening of the ellipsoid used is 1/294.978698.

  7. How does the data set describe geographic features?

    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
Digital 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 Standard for the Digital Raster Graphic
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Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

    • Idaho Geospatial Data Clearinghouse
    • U.S. Geological Survey (USGS)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Bruce Godfrey
    Idaho Geospatial Data Clearinghouse
    GIS Specialist
    Box 442350
    Moscow, ID 83844-2350
    USA

    208.885.6463 (voice)
    bgodfrey@uidaho.edu
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Why was the data set created?

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 DLG data. DRG's can also be merged with other digital data, e.g. DEM's or DOQ's, to produce a hybrid digital file.

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How was the data set created?

  1. Where did the data come from?

    DRG (source 1 of 1)

    Idaho Geospatial Data Clearinghouse, Unpublished Material, Seamless Mosaic of Digital Raster Graphics of Idaho: Idaho Geospatial Data Clearinghouse, Moscow, ID USA.

    Type of source media: ArcSDE Raster Dataset
    Source scale denominator: 24000
    Source contribution: 
    Seamless mosaic of digital raster graphics for Idaho in ArcSDE Raster Dataset format, IDTM projection, NAD27 datum.

  2. What changes have been made?

    Date: 2002 (change 1 of 1) 
    Created and ArcIMS Image Service using the above mentioned souce ArcSDE layer. Additional layers were included in the service for reference purposes.

    Person responsible for change:
    Bruce Godfrey
    Idaho Geospatial Data Clearinghouse
    GIS Specialist
    Box 442350
    Moscow, ID 83844-2350
    USA

    208.885.6463 (voice)
    bgodfrey@uidaho.edu

    Data sources used in this process:
    • DRG

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How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    The DRG is an 8-bit color image that employs a color palette to ensure uniform colors throughout a particular DRG series.

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    All DRGs that cover Idaho are included in the map service.

The 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 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.

  5. How consistent are the relationships among the observations, including topology?

    Not Applicable

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How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access constraints: None
Use constraints: 
None

Distributor 1 of 1

  1. Who distributes the data set?

    Bruce Godfrey
    Idaho Geospatial Data Clearinghouse
    GIS Specialist
    Box 442350
    Moscow, ID 83844-2350
    USA

    208.885.6463 (voice)
    bgodfrey@uidaho.edu

  2. What's the catalog number I need to order this data set?

    Live Data and Maps

  3. What legal disclaimers am I supposed to read?

    Although these data have been processed successfully on a computer system at the Idaho Geospatial Data Clearinghouse, no warranty, expressed or implied, is made regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty.

  4. How can I download or order the data?

  5. Is there some other way to get the data?

  6. What hardware or software do I need in order to use the data set?

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Who wrote the metadata?

Dates:
Last modified: 20050413

Metadata author:
Bruce Godfrey
Idaho Geospatial Data Clearinghoue
GIS Specialist
Box 442350
Moscow, ID 83844-2350
USA

208.885.6463 (voice)
bgodfrey@uidaho.edu

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata(FGDC-STD-001-1998)

Metadata extensions used:
  • http://www.esri.com/metadata/esriprof80.html

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