Mosaic of Illinois Digital Orthophoto Quadrangles in UTM Zone 16, NAD83, 2005 Photography

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Frequently-anticipated questions:


What does this data set describe?

Title:
Mosaic of Illinois Digital Orthophoto Quadrangles in UTM Zone 16, NAD83, 2005 Photography
Abstract:
This data set is an SDE raster mosaic of DOQs from year 2005 that occur within the UTM Zone 16 portion of Illinois. The data are stored in the "as delivered" spatial reference of UTM Zone 16, NAD83 with a 0.5-meter ground resolution. This raster mosaic can be used in conjunction with the raster mosaics named IL_DOQ_2005_MOSAIC_UTM15_RAS and IL_CUA_2005_MOSAIC_UTM16_RAS to provide full 2005 orthophoto coverage of Illinois.

The raster mosaic was constructed using uncompressed GeoTIFF images and ArcSDE 9.1 command-line functions. It is stored in the SDE database with LZ77 compression. The original image tiles were not resampled in the mosaicking process and had exact side-by-side pixel registration. This means the SDE raster layer preserves the exact pixel location and cell values of the source images. The data consume 512 gigabytes of disk space in 15,680,818 database rows. The in-processing occurred over the period 20060612 to 20060920 as the data were delivered is several lots by the USGS.

[Begin excerpt from USGS metadata]

A 0.5 meter resolution panchromatic (B and W) USGS Digital Orthophoto Quarter-quadrangle (DOQQ) (sic) A DOQQ is a raster image in which displacement in the image caused by sensor orientation and terrain relief has been removed. A DOQQ combines the image characteristics of a photograph with the geometric qualities of a map. The geographic extent of the DOQQ is equivalent to a quarter of a 7.5-minute map (3.75 minutes of latitude and longitude) with overedge . The overedge ranges from a minimum of 50 meters to 300 meters beyond the extremes of the primary and secondary corner ticks. DOQQs are produced with a 1-meter ground sample distance (GSD) and are cast on the Universal Transverse Mercator (UTM) projection on the North American Datum of 1983 (NAD83). Primary (solid) and secondary (dashed) corner ticks are burned into the image to indicate the geographic corners of the DOQQ. The primary ticks always show the NAD83 corners. The secondary ticks show either the NAD27 or the local horizontal datum in use in a specific area (e.g. the Puerto Rico datum, the Hawaiian datum). Each DOQQ is produced to meet a National Map Accuracy Standard (NMAS) for 1:12000 scale maps (10.16 meters radial error at a 90% probability). Each DOQQ is formatted with a variable length ASCII header followed by a series of 8-bit image data lines. The ASCII header is padded to equal the length of one image line. The header contains information on file organization, display (samples and lines), georeferencing, and production sources. The file structure for a native format DOQQ is analogous to a raw raster BIL (panchromatic) or BIP (RGB color). DOQQs are nominally produced from National Aerial Photography Program (NAPP) source imagery flown at 20,000 feet above average ground using a single source image for each DOQQ. NAPP imagery is flown leaf-off in deciduous vegetation regions.

[End excerpt from USGS metadata]

The radiometric image brightness values are stored as 256 gray levels ranging from 0 to 255.

  1. How should this data set be cited?

    U.S. Geological Survey, Illinois State Geological Survey, and Surdex Corporation and Science Applications International Corporation (SAIC), 20060920, Mosaic of Illinois Digital Orthophoto Quadrangles in UTM Zone 16, NAD83, 2005 Photography: ISGS GIS Database GISDB.IL_DOQ_2005_MOSAIC_UTM16_RAS, Illinois State Geological Survey, Champaign, IL.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -90.220692
    East_Bounding_Coordinate: -87.423217
    North_Bounding_Coordinate: 42.603591
    South_Bounding_Coordinate: 36.916633

  3. What does it look like?

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

    Beginning_Date: 18-Feb-2005
    Ending_Date: 04-May-2005
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: remote-sensing image

  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. It contains the following raster data types:

      • Dimensions 1254317 x 453429 x 1, type Pixel

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 16
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -87.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 0.500000
      Ordinates (y-coordinates) are specified to the nearest 0.500000
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    [Begin excerpt from USGS metadata]

    Panchromatic orthoimagery is organized in a single channel. Each pixel is assigned a gray-scale value from 0-255 with 0 representing black and 255 representing white. Areas where data is incomplete due to lack of full image coverage are represented with the numeric value of 0 or 128.

    [End excerpt from USGS metadata]

    Entity_and_Attribute_Detail_Citation:
    U.S. Department of the Interior, U.S. Geological Survey, 1996, Standards for Digital Orthophotos: Reston, VA.


Who produced the data set?

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

  2. Who also contributed to the data set?

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

    Contact_Instructions: Please refer to the Distribution Information section.


Why was the data set created?

[Begin excerpt from USGS metadata]

This data depicts geographic features on the surface of the earth. DOQQs serve a variety of purposes, from interim base maps to field references for earth science investigations and analysis. The DOQQ is useful as a layer in a geographic information system (GIS) and as a tool for performing digital map revision. DOQQs form the medium-resolution image base for The National Map.

[End excerpt from USGS metadata]

These data are appropriate for use in local and regional thematic analysis. The data are not appropriate as a geodetic, legal or engineering base. The data set serves as an important base cartographic element for many types of maps and has been widely distributed and used outside the ISGS. The data set was not and is not intended as a substitute for surveyed locations, such as can be determined by a registered Public Land Surveyor. Although useful in a GIS as a reference base layer for maps, the data set has no legal basis in the definition of boundaries or property lines.


How was the data set created?

  1. From what previous works were the data drawn?

    PHOTO (source 1 of 4)
    Corporation, Surdex, 2005, Various NAPP photographs covering the mosaicked area.

    Type_of_Source_Media: stable-base material
    Source_Scale_Denominator: 40000
    Source_Contribution:
    [Begin excerpt from USGS metadata]

    Stable-base aerial photography acquired at 1:40,000 scale using only metric aerial cameras with USGS calibration certificates. Provides the imagery for the digital orthoimage. Film is panchromatic.

    [End excerpt from USGS metadata]

    DEM (source 2 of 4)
    U.S. Geological Survey, 2003, USGS 1-arcsec NED.

    Type_of_Source_Media: Hard Drive
    Source_Contribution:
    [Begin excerpt from USGS metadata]

    USGS 1-arcsec National Elevation Dataset for the entire United States that was broken down into 1 degree cells.

    [End excerpt from USGS metadata]

    CONTROL (source 3 of 4)
    Corporation, Surdex, 2005, Project Photo Control.

    Type_of_Source_Media: CD-ROM
    Source_Contribution:
    [Begin excerpt from USGS metadata]

    Horizontal and vertical control used to establish positions and elevations for reference and correlation purposes and as input to the aerotriangulation process. Control consists of both Airborne GPS to provide camera station positions and photoidentifiable surveyed ground control for ground reference.

    [End excerpt from USGS metadata]

    (source 4 of 4)
    United States Geological Survey, 2005, GeoTIFF Collection on Hard Drive.

    Type_of_Source_Media: hard drive
    Source_Contribution:
    The GeoTIFF images were delivered to ISGS from USGS on a series of hard drives.

  2. How were the data generated, processed, and modified?

    Date: range 20051118 - 20060728 (process 1 of 1)
    The production procedures, instrumentation, hardware and software used in the collection of standard USGS DOQ's vary depending on systems used at the contract, cooperator or USGS production sites. The majority of DOQ datasets are acquired through government contract. This process step describes the process used by the contractor (Surdex) for this USGS DOQ data set. Additional detail is included in subsequent processing steps for processing done by the ISGS.

    [Begin excerpt from USGS metadata]

    Source imagery was collected using four cameras (two Wild RC-30 and two Jena LMK), all have 6" focal lengths and a current calibration by USGS. The imagery was processed by HAS Images Inc. in Dayton, OH. Airbone GPS data was processed by Surdex Corporation. Image negatives were scanned at 10-micrometer resolution on Leica DSW Image Scanners and dodge using SurDodge software by Surdex. The scanned images were then used as input, along with Airborne GPS data and camera calibration data in Intergraph's ImageStation Automatic Triangulation (ISAT) for point mensuration. An assessment of the USGS National Elevation Dataset (NED) revealed several areas of insufficient data, at which other DEM sources obtained by Surdex was (sic) used. The aero triangulation parameter data, used with the scanned and dodged imagery were orthorectified using the modified elevation models and Surdex orthorectification software. Some orthorectified images were then mosaicked, if necessary, to reduce minor image defects. Radiometric balancing achieved using Inpho's OrthoVista, as necessary, to produce a consistent image tone for DOQQs. Product tiles were then extracted and converted to GeoTIFF format written to hard drive for delivery.

    [End excerpt from USGS metadata]

    The Surdex processing was done on LH Systems DSW700 Film Scanners, Surdex SurDodge Software, Intergraph's ISAT v04.04.17, Surdex Snoop tool, Surdex DOQQDB Production Software, Surdex developed orthorectification software, Inpho Orthovista software v4.0, Windows 2000 and Windows XP Operating System. SAIC QVerify V0.1 Software, SAIC QSideview V0.1., SUNW Ultra-4, Solaris OS V5.9.

  3. What similar or related data should the user be aware of?

    , ISGS Terms of Use.

    Online Links:

    , University of Illinois Web Privacy Notice.

    Online Links:

    , University Copyright Policy (stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4).

    Online Links:

    , Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign.

    Online Links:


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

  1. How well have the observations been checked?

    For original, uncompressed DOQs (GeoTIFF format) as delivered by USGSand Surdex:

    [Begin excerpt from USGS metadata]

    The digital dodging software developed by Surdex is used to counter the effects of haze and sun angle illumination on the film photography. This procedure has been proven to provide a distinct advantage in minimizing the need for extensive radiometric balancing and improves automatic pass/tie point collection during the aerotriangulation phase. The net affect of this program is to drive the source image closer to a histogram with a nearly Gaussian distribution. The output of this program will always produce an image with full dynamic range, nearly regardless of the source image. Minimal radiometric balancing was achieved using Inpho's Ortho Vista software.

    [End excerpt from USGS metadata]

  2. How accurate are the geographic locations?

    For DOQs "as delivered" by USGS:

    [Begin excerpt from USGS metadata]

    Random selection of 5% of the DOQQ tiles for excessive edge match offset.

    [End excerpt from USGS metadata]

    For SDE DOQ mosaic developed by ISGS:

    The pixels preserve the exact position of the source imagery. This was verified in ArcMap software by overlaying a random sample of 10% of the source images with the SDE raster mosaic, zooming into one or more corners of the source image to a scale of 1:10 or greater, and comparing the locations of the corners of the corner-most pixel in the source image to the corresponding pixel in the raster mosaic.

  3. How accurate are the heights or depths?

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

    [Begin excerpt from USGS metadata]

    DOQQ images are visually inspected for completeness to ensure that no gaps or image misplacements exist within the 3.75-minute image area or the overedge coverage. DOQQs can be derived by mosaicking multiple images to ensure complete coverage. and between adjacent images. (sic) DOQQs are nominally produced from National Aerial Photography Program (NAPP) source imagery flown at 20,000 feet above average ground using a single source image for each DOQQ. NAPP imagery is flown leaf-off in deciduous vegetation regions. Source imagery is nominally cloud free. Coastal areas and international boundary regions may have areas without images (void areas) in parts of the coverage. These void areas have a radiometric value of either zero (black) or 128 (uniform gray). DOQQs nominally are produced with overedge coverage. This coverage is variable and may range from a minimum of 50 meters to a maximum of 300 meters beyond the extremes of the primary or secondary corners. The resulting DOQQ is a rectangle whose size may vary in relation to adjoining DOQQs.

    [End excerpt from USGS metadata]

    Regarding DOQ mosaic as subsequently processed by ISGS:

    All areas in the UTM 16 portion of the state of Illinois are represented, except the greater Chicago metropolitan area.

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

    [Begin excerpt from USGS metadata]

    All DOQQ header data and image file sizes are validated using USGS software before being archived. This validation process ensures correct physical format and field values for header elements. Logical relationships between header elements are tested. Overlap regions between individual DOQQs are visually inspected for excessive horizontal displacement.

    [End excerpt from USGS metadata]

    No subsequent logical validation has been performed.


How can someone get a copy of the data set?

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

Access_Constraints:
ISGS information must be obtained directly from the ISGS or from an authorized distributor. Be aware that ISGS information obtained from an unauthorized third party may have been altered subsequent to original distribution, or may no longer be current.

Any access to these data, Web sites, computer systems, electronic services, and electronic networks is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice.

Links to these are provided in the Cross References section.

Use_Constraints:
ISGS information is the property of and copyrighted by the Board of Trustees of the University of Illinois with all rights reserved.  University copyright policy is stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4. A link is provided in the Cross References section.

Individuals or entities may make fair use of copyrighted ISGS material, such as reproducing a single figure or table, or using a brief text quotation, without obtaining formal permission, but in all cases the Illinois State Geological Survey must be credited as the source of the material. To reproduce ISGS information beyond the fair use standard, permission must be obtained from the ISGS Information Office, 615 East Peabody Drive, Champaign, Illinois 61820, 217-333-4747, isgs@isgs.illinois.edu. License fees and a license agreement may be required, depending on the proposed usage.

Any use of these data is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section.

Map information is to be used at a scientifically and cartographically appropriate scale, that is, at a scale no greater than indicated on the map or as described in the documentation of the map or map data.  Map information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. Map information has no legal basis in the definition of boundaries or property lines and is not intended as a substitute for surveyed locations such as can be determined by a registered Public Land Surveyor.

The data do not replace the need for detailed site-specific studies.

  1. Who distributes the data set? (Distributor 1 of 1)

    Information Office, Illinois State Geological Survey (ISGS), a division of the Institute of Natural Resource Sustainability (INRS) of the University of Illinois
    615 East Peabody Drive
    Champaign, Illinois 61820
    USA

    217-333-4747 (voice)
    isgs@isgs.illinois.edu

    Hours_of_Service: 8:00 a.m. - 4:30 p.m., Monday-Friday, U.S. Central Time
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    Refer to the Legal Notices of Terms and Conditions of the University of Illinois Web Privacy Policy (there is a link in the Cross References section) for policy statements regarding the following:

    Disclaimer of Liability Disclaimer of Warranties and Accuracy of Data Disclaimer of Endorsement Disclaimer for External Links Disclaimer of Duty to Continue Provision of Data Security Choice of Law

    By obtaining these data you agree to the provisions of the University of Illinois Web Privacy Policy, regardless of the manner in which the information was obtained.

  4. How can I download or order the data?

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

    The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, ESRI formats can be imported into many different GIS software packages. It is expected that customers who obtain these data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind.


Who wrote the metadata?

Dates:
Last modified: 24-Feb-2009
Metadata author:

Contact_Instructions: Please refer to the Distribution Information section.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Illinois Natural Resources Geospatial Data Clearinghouse

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