sidescan_trk_06015.shp - Tracklines of sidescan sonar data collected by the U.S. Geological Survey offshore of the Chandeleur Islands, LA, 2006 (polylines)

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Frequently-anticipated questions:

What does this data set describe?

Title:
sidescan_trk_06015.shp - Tracklines of sidescan sonar data collected by the U.S. Geological Survey offshore of the Chandeleur Islands, LA, 2006 (polylines)
Abstract:
In 2006 and 2007, the U.S. Geological Survey, in partnership with Louisiana Department of Natural Resources and the University of New Orleans, conducted geologic mapping to characterize the sea floor and shallow subsurface stratigraphy offshore of the Chandeleur Islands in Eastern Louisiana. The mapping was carried out during two cruises on the R/V Acadiana. Data were acquired with the following equipment: an SEA Ltd SwathPlus interferometric sonar (234 kHz), Klein 3000 dual frequency sidescan sonar, and an Edgetech 512i chirp subbottom profiling system. The long-term goal of this mapping effort is to produce high-quality geologic maps and geophysical interpretations that can be utilized to investigate the impact of Hurricane Katrina in 2005 and to identify sand resources within the region.
  1. How should this data set be cited?

    U.S. Geological Survey, 2009, sidescan_trk_06015.shp - Tracklines of sidescan sonar data collected by the U.S. Geological Survey offshore of the Chandeleur Islands, LA, 2006 (polylines): Open-File Report 2008-1195, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Baldwin, Wayne E. , Pendleton, Elizabeth A. , and Twichell, David C. , 2009, Geophysical Data from offshore of the Chandeleur Islands, Eastern Mississippi Delta: Open-File Report 2008-1195, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -88.899490
    East_Bounding_Coordinate: -88.751099
    North_Bounding_Coordinate: 30.119234
    South_Bounding_Coordinate: 29.702248

  3. What does it look like?

    <http://pubs.usgs.gov/of/2008/1195/images/sonar_trk.jpg> (JPEG)
    Sidescan sonar tracklines offshore of the Chandeleur Isands, LA

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

    Beginning_Date: 08-Jul-2006
    Ending_Date: 19-Jul-2006
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

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

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • String (506)

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

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000000. Longitudes are given to the nearest 0.000000. Latitude and longitude values are specified in Decimal degrees.

      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?

    sidescan_trk_06015
    ESRI polyline shapefile (Source: ESRI)

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    JD
    Julian Day in which sidescan trackline data were collected (Source: U.S. Geological Survey)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Year
    Calendar year in which sidescan trackline data were collected (Source: U.S. Geological Survey)

    Line
    line and file number for corresponding sidescan sonar filename. This information is used during data acquisition, storage, and processing. (Source: U.S. Geological Survey)

    length
    length of line segment in UTM Zone 16 N meters (Source: U.S. Geological Survey)

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?

    David C. Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov

Why was the data set created?

This data set contains tracklines for approximately 1900 km of sidescan sonar data collected by the U.S. Geological Survey during a 2006 geophysical cruise offshore of the Chandeleur Islands, LA.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    U.S. Geological Survey.

    Type_of_Source_Media: disc
    Source_Contribution:
    Trackline acquisition at sea (2006): These sidescan sonar data were collected with a Klein 3000 dual frequency sidescan sonar towfish on the R/V Acadiana of Loreauville, LA. These data were acquired using SonarPro Software (version: none). Tracklines are spaced 100 to 125 m apart in the shore parallel direction.

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

    Date: 2006 (process 1 of 3)
    Navigation was extracted from the raw sidescan sonar data (*XTF format) in XSonar (version: none) using the 'demultiplex' function (Danforth and others, 1991). Navigation was exported as comma-separated text from XSonar for input into ArcGIS (version 9.2).

    Person who carried out this activity:

    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2226 (voice)
    (508) 457-2310 (FAX)
    wbaldwin@usgs.gov

    (process 2 of 3)
    In ArcCatalog (version 9.2; Build 1420), navigation text was converted to a point feature class by right-clicking on the comma separated text file -- Create Feature Class -- from XY table.

    Person who carried out this activity:

    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2226 (voice)
    (508) 457-2310 (FAX)
    wbaldwin@usgs.gov

    (process 3 of 3)
    VAC Extras tool (version: 1.97 FeatConv - Points to Line v2; USGS in house software) was then used within ArcMap (version 9.2; Build 1420) to convert the navigation points to a trackline shapefile. The trackline shapefiles were edited to remove spurious fixes, and a length field was created and populated using 'Calculate Geometry', which can be accessed by right-clicking on the attribute field name in the table view.

    Person who carried out this activity:

    Elizabeth A. Pendleton
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2259 (voice)
    (508) 457-2310 (FAX)
    ependleton@usgs.gov

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

    Danforth, W.W., O'Brien, T.F., and Schwab, W.C., 1991, USGS image processing system: near real-time mosaicking of high-resolution sidescan-sonar data: Jan. 1991, Sea Technology.

    Danforth, William W. , 1997, XSonar/ShowImage: A complete system for rapid sidescan-sonar processing and display.: Open-File Report 97-686, U.S. Geological Survey.

    Paskevich, V.F., 1992, Digital mapping of sidescan sonar data with the Woods Hole Image Processing System software: Open-File Report 92-536, U.S. Geological Survey.

    Paskevich, Valerie, 1996, MAPIT: An improved method for mapping digital sidescan sonar data using the Woods Hole Image Processing System (WHIPS) Software: Open-File Report 96-281, U.S. Geological Survey.

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

  1. How well have the observations been checked?

    All attributes were checked in a consistent manner.

  2. How accurate are the geographic locations?

    These data were navigated with a Differential Global Positioning System (DGPS) mounted above the interferometric sonar head. Unless noted, all DGPS data are referenced to WGS84. The layback distance between towed sidescan sonar fish and the mounted GPS antennae were measured on the ship and corrected for these navigation data.

  3. How accurate are the heights or depths?

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

    Navigation from all the sidescan sonar tracklines was used to generate this shapefile.

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

    Any spurious data points were removed during processing.

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:
The Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.

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

    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2226 (voice)
    (508) 457-2310 (FAX)
    wbaldwin@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?

    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. 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?

    This zip file contains data available in Environmental Systems Research Institute (ESRI) polyline shapefile format. The user must have ArcGIS or ArcView 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing the data. A free data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 28-Jan-2009
Metadata author:
Elizabeth A. Pendleton
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA 02543-1598
USA

508-548-8700 x2259 (voice)
(508)-457-2310 (FAX)
ependleton@usgs.gov

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

Generated by mp version 2.8.25 on Wed Jan 28 14:36:04 2009