ASV178.TIF - Autonomous Surface Vehicle Sidescan-sonar mosaic from North Spur, Apalachicola Bay, Florida

Metadata also available as - [Outline] - [Parseable text]

Frequently-anticipated questions:

What does this data set describe?

Title:
ASV178.TIF - Autonomous Surface Vehicle Sidescan-sonar mosaic from North Spur, Apalachicola Bay, Florida
Abstract:
These data were collected under a cooperative mapping program between the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration Coastal Services Center (NOAA\CSC), and the Apalachicola National Estuarine Research Reserve (NERR). The primary objectives of this program were to collect marine geophysical data to develop a suite of seafloor maps to better define the extent of oyster habitats, the overall seafloor geology of the bay and provide updated information for management of this resource. In addition to their value for management of the bay's oyster resources, the maps also provide a geologic framework for scientific research and the public.
High resolution bathymetry, backscatter intensity, and seismic profile data were collected over a 230 square kilometers of the floor of the bay. The study focused on the Apalachicola Bay and Western St. George Sound portions of the estuary mostly in depths > 2.0 meters.
  1. How should this data set be cited?

    U.S. Geological Survey, 2007, ASV178.TIF - Autonomous Surface Vehicle Sidescan-sonar mosaic from North Spur, Apalachicola Bay, Florida: Open-File Report 2006-1381, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Twichell, David C. , Andrews, Brian D. , Edmiston, H. Lee , and Stevenson, William R. , 2007, Geophysical Mapping of oyster habitats in a shallow estuary; Apalachicola Bay, Florida: Open-File Report 2006-1381, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -85.046405
    East_Bounding_Coordinate: -85.030700
    North_Bounding_Coordinate: 29.691155
    South_Bounding_Coordinate: 29.680102

  3. What does it look like?

    <http://pubs.usgs.gov/of/2006/1381/GIS/thumbnails/asv178.jpg> (JPEG)
    grey-scale image of sidescan-sonar mosaic

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

    Calendar_Date: 27-Jun-2006
    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 1200 x 1500 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 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    There are no attributes associated with a GeoTIFF image. Image pixel values contain acoustic reflectivity values normalized to an 8-bit data range (0-255). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values).

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?

    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov

Why was the data set created?

These data are high-resolution acoustic backscatter measurements collected over part of North Spur in Apalachicola Bay, Florida. These data were collected using the Autonomous Surface Vessel (ASV) IRIS primarily over known oyster bars in waters less than 1-2 meters deep.

How was the data set created?

  1. From what previous works were the data drawn?

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

    Date: Sep-2006 (process 1 of 1)
    The sidescan-sonar data were acquired with a EdgeTech 4200 FS dual-frequency sidescan-sonar system. The EdgeTech 4200 operates in a frequency range of 100 and 400 kHz. Data were collected and logged to onboard in .jsf format using EdgeTech JStar acquisition software. All jsf files for each Julian day were imported to Xsonar and converted to Xsonar format using the 400 kHz channel. Each file was corrected for slant range and beam pattern corrections as described in Danforth (1997). The individual line files were mosaiced in Xsonar with a range cutoff of 25m. The composite mosaic was exported as a GeoTIFF image, with an associated world file.

    Person who carried out this activity:

    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov

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

    Danforth, W.W., 1997, Xsonar/ShowImage: A complete system for rapid sidescan-sonar processing and display: Open-File Report 97-686, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.

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 ASV used RTK-GPS for navigation. RTK-GPS is assumed to be accurate within 1-2 meters. All GPS/DGPS data are referenced to WGS84. The sidescan-sonar transducers are mounted on a metal frame between the two pontoons about 0.5m below water surface directly below the GPS antenna.

  3. How accurate are the heights or depths?

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

    Although both the 100 kHz and 400 kHz frequency data were collected, only the high frequency 400 kHz data were processed and included in this mosaic. Small differences in contrast stretch (DN values) exist because of variations in sea and weather conditions on each survey day.

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

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:
Data are not intended for navigational use.
These data should not be used at resolutions for which it is not intended.
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.

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

    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov

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

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.
    Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  4. How can I download or order the data?

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

    These data are available in GeoTIFF format. The user must have software capable of viewing a GeoTIFF data file.

Who wrote the metadata?

Dates:
Last modified: 27-Aug-2007
Metadata author:
U.S. Geological Survey
c/o Brian Andrews
Geographer
384 Woods Hole Rd.
Woods Hole, MA 02543-1598
USA

508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov

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

Generated by mp version 2.9.2 on Mon Aug 27 13:44:58 2007