2007 MrSID Image of St. John Utilized to derive Benthic Habitat Maps (18064_c7_nw.sid)

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Frequently anticipated questions:


What does this data set describe?

Title:
2007 MrSID Image of St. John Utilized to derive Benthic Habitat Maps (18064_c7_nw.sid)
Abstract:
This MrSID (.sid) file is an orthophoto mosaic from a collection of GeoTIFF format natural color and false color infrared orthophotos covering the islands of Puerto Rico, Culebra, Vieques, St. Thomas, St. John, and St. Croix (USVI). An orthophoto is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthophotography combines the image characteristics of a photograph with the geometric qualities of a map. The source imagery was obtained from November 2006 through March 2007 and used to produce orthophotos with a one foot ground sample distance (GSD). Imagery was acquired at 0.9 foot GSD resolution. Flight height maintained during mission was 8,650 feet AGL. The imagery was captured at 12-bit radiometric resolution and converted to 8-bit radiometric resolution during post processing. The imagery was captured with 30% sidelap between all adjacent flight lines. The PRVI project area was divided into 20 flight blocks due to neccessary base station and flight line length requirements. The imagery was obtained and processed by all digital means beginning with data acquisition using an ADS40 digital sensor. The orthophotos are also available in GeoTIFF form from the distributor.
Supplemental_Information:
The data design specifications for this product includes several directed to ensure its quality, consistency, and useability. These specifications address some of the technical issues associated with orthoimage production: 1) the tops of buildings and other structures elevated above the surface of the ground 'tilt' away from the center point of the source photography and from their own bases as a result of perspective and their height which is not compensated for in digital elevation models of the ground surface and 2) individual orthoimages may be assembled from several source images (strips).

Resource Description: The data are being provided on an 'as is' basis. The Corps specifically disclaims any warranty, expressed or implied, including, but not limited to, the implied warranties or merchantability and fitness for a particular use. The entire risk as to quality and performance is with the user. In no event will the Corps or its staff be liable for any direct, indirect, incidental, special, consequential, or other damages, including loss of profit, arising out of the use of these data even if the Corps has been advised of the possibility of such damages. All data are intended for resource management use.

  1. How should this data set be cited?

    United States Army Corps of Engineers, 20080217, 2007 MrSID Image of St. John Utilized to derive Benthic Habitat Maps (18064_c7_nw.sid): 3001, Inc., 401 Dividend Drive, Suite K, Peachtree City, GA 30269.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -64.875938
    East_Bounding_Coordinate: -64.811540
    North_Bounding_Coordinate: 18.374803
    South_Bounding_Coordinate: 18.310878

  3. What does it look like?

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

    Beginning_Date: Sep-2007
    Ending_Date: Oct-2007
    Currentness_Reference: Date of image acquisition

  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. It contains the following raster data types:

      • Dimensions 23022 x 22133 x 1, type Pixel

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

      The map projection used is Lambert Conformal Conic.

      Projection parameters:
      Standard_Parallel: 18.433333
      Standard_Parallel: 18.033333
      Longitude_of_Central_Meridian: -66.433333
      Latitude_of_Projection_Origin: 17.833333
      False_Easting: 200000.000000
      False_Northing: 200000.000000

      Planar coordinates are encoded using Row and Column
      Abscissae (x-coordinates) are specified to the nearest 0.304800
      Ordinates (y-coordinates) are specified to the nearest 0.304800
      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.

  7. How does the data set describe geographic features?


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?

    U.S. Army Corps of Engineers
    1222 Spruce Street
    St. Louis, MO 63103-2833
    US

    314-331-8385 (voice)
    314-331-8071 (FAX)
    Robert.D.Mesko@mvs02.usace.army.mil


Why was the data set created?

The purpose of the project is to provide the United States Army Corps of Engineers with current year digital orthophotos covering all of Puerto Rico and the US Virgin Islands. The Corps regularly uses digital orthophotos to support regulatory, land management and acquistion, planning, engineering and habitat restoration projects. The data may also become available to local, state and other federal agencies for their specific management and analysis needs. The one-foot resolution data collected for this project is higher resolution than the previous island-wide collection in 2004, which was one-meter resolution.


How was the data set created?

  1. From what previous works were the data drawn?

    dig_aer_img (source 1 of 3)
    3001, Inc., 20080217, Digital Aerial Imagery for 2006-2007 PRVI Orthophotography: 3001, Inc., 401 Dividend Drive, Suite K, Peachtree City, GA 30269.

    Other_Citation_Details: Additional Information: (770) 631-0903
    Type_of_Source_Media: disc
    Source_Scale_Denominator: 2400
    Source_Contribution:
    Flight planning, image acquisition, image processing and image packaging.

    photo_control (source 2 of 3)
    RLDA, 20070115, Ground Control for 2006-2007 PRVI Orthophotography: RLDA, PO Box 41033, San Juan, Puerto Rico, 00940.

    Other_Citation_Details: Additional Information: (787)268-6097
    Type_of_Source_Media: disc
    Source_Scale_Denominator: 2400
    Source_Contribution:
    Horizontal and vertical control used to establish positions and elevations for reference and correlation purposes and as input to the aerotriangulation process.

    ortho_dem (source 3 of 3)
    3001, Inc, 20050201, DEM for Orthorectification of 2006-2007 PRVI Orthophotography: 3001, Inc., 401 Dividend Drive, Suite K, Peachtree City, GA 30269.

    Other_Citation_Details: Additional Information: (770) 631-0903
    Type_of_Source_Media: disc
    Source_Scale_Denominator: 2400
    Source_Contribution: Ground elevations used for orthorectification process

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

    Date: 17-Feb-2008 (process 1 of 1)
    Ground control consisted of photo identifiable surveyed points. The imagery was collected at an altitude of 8650 ft using an ADS40 digital sensor. Image quality was verified during the post flight review phase. Factors considered during this review included but were not limited to the presence of smoke and/or cloud cover, contrails, light conditions and sun glint.

    The triangulated strips were rectified with a recent DEM of the area provided by 3001, Inc. The vertical accuracy of the DEM varies based on the elevation postings and is generally estimated at 30-45cm. The red, green and blue bands were combined to generate a final natural color orthophoto, and the near - infrared, red and green bands were combined to generate a final false color infrared orthophoto.

    The ADS40 sensor collects twelve bit image data which requires radiometric adjustment for output in standard eight bit image channels. Converting to eight bit results in a reduction of the color range from 4096 to 256 - thus loss of radiometric detail is inevitable. The extra dynamic range of the sensor permits greater object differentiation in shadows and in bright areas. The sixteen bit dynamic range permitted the imagery to be more effectively color balanced than is possible with eight bit imagery. This was accomplished by performing tonal enhancements immediately prior to the reduction from sixteen bit to eight bit data. In addition to color banancing these eight bit images were adjusted to create seamless imagery to the highest extent practically achievable.

    The imagery was mosaicked using a combination of automated and manual seamlines generation. Project pecified tiles were extracted from the mosaic. Final image tiles were reviewed for artifacts and anomalies and adjusted as part of quality control procedures. When necessary, local corrections to the imagery were performed to minimize such effects.

    Person who carried out this activity:

    Peter Briere
    3001, Inc
    401 Dividend Drive, Suite K
    Peachtree City, GA 30269

    (770) 631-0903 (voice)
    (770) 631-0820 (FAX)
    pbriere@3001inc.com

    Hours_of_Service: 8:00 a.m. to 5:00 p.m.
  3. What similar or related data should the user be aware of?


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

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    The accuracy value was determined by measuring photo-identifiable control points collected with GPS survey methods in the orthophotos.

  3. How accurate are the heights or depths?

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

    These data cover all of the islands of Puerto Rico, Culebra, Vieques, and the US Virgin Islands. Each orthophoto has an overedge of approximately 30 meters on all sides of its centering 1.875 minute cell.

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

    Sample points taken from overlapping areas of adjacent image strips that contributed image chips to each orthophoto tile are typically consistent to the 2-3 pixel level. This not only ensures that a consistent mosaic can be created from the adjacent image strips acquired with the ADS40 pushbroom scanner but also means that the images have good precision and as a group are spatially self-consistent.


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. Acknowledgment of the United States Army Corps of Engineers would be appreciated for products derived from these data.

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

    U.S. Army Corps of Engineers
    1222 Spruce Street
    St. Louis, MO 63103-2833
    US

    314-331-8385 (voice)
    314-331-8071 (FAX)
    Robert.D.Mesko@mvs02.usace.army.mil

    Hours_of_Service: Monday through Friday 8:00 AM to 5:00 PM (Central Time)
  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Translation of files to formats other than those described here is the sole responsibility of individuals downloading the data.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 20-Dec-2012
Last Reviewed: 15-Mar-2010
Metadata author:
U.S. Army Corps of Engineers
1222 Spruce Street
St. Louis, MO 63103-2833
US

314-331-8385 (voice)
314-331-8071 (FAX)
Robert.D.Mesko@mvs02.usace.army.mil

Hours_of_Service: Monday through Friday 8:00 AM to 5:00 PM (Central Time)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.13 on Sun Apr 20 10:40:29 2014