Enhanced SIS-1000 sidescan sonar mosaic of a minibasin on the Louisiana upper continental slope - UTM, zone 15, WGS84 (SIS_ENUTM.TIF)

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Frequently anticipated questions:

What does this data set describe?

Title:
Enhanced SIS-1000 sidescan sonar mosaic of a minibasin on the Louisiana upper continental slope - UTM, zone 15, WGS84 (SIS_ENUTM.TIF)
Abstract:
Since 1982 the, U.S. Geological Survey (USGS) has collected a large amount of surficial and shallow subsurface geologic information in the deep parts of the Gulf of Mexico. These data include digital sidescan sonar imagery, digital seismic-reflection data, and descriptions and analyses of piston and gravity cores. The data were collected during several different projects that addressed surficial and shallow subsurface geologic processes. Some of these data sets have already been published, but the growing interest in the occurrence and distribution of gas hydrates in the Gulf of Mexico warrants integrating these existing data and associated interpretations into a GIS to provide regional background information for ongoing and future gas hydrate research.
  1. How might this data set be cited?
    Twichell, David, Cross, VeeAnn, and Danforth, William, 2005, Enhanced SIS-1000 sidescan sonar mosaic of a minibasin on the Louisiana upper continental slope - UTM, zone 15, WGS84 (SIS_ENUTM.TIF): Open-File Report 2005-1071, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    D.C., Twichell, V.A., Cross, Paskevich, V.F., Hutchinson, D.R., Winters, W.J., and Hart, P.E., 2005, GIS of selected geophysical and core data in the northern Gulf of Mexico continental slope collected by the U.S. Geological Survey: Open-File Report 2005-1071, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details: 1 DVD-ROM
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -91.868023
    East_Bounding_Coordinate: -91.581642
    North_Bounding_Coordinate: 27.833329
    South_Bounding_Coordinate: 27.699997
  3. What does it look like?
    https://pubs.usgs.gov/of/2005/1071/data/sidescan/imagery/sis1000/enhanced/utm/sis_enutm-thumb.gif (GIF)
    Thumbnail image of the SIS1000 sidescan sonar mosaic of a minibasin on the Louisiana upper continental slope.
    https://pubs.usgs.gov/of/2005/1071/data/sidescan/imagery/sis1000/enhanced/utm/sis_enutm.gif (GIF)
    Overview image of the SIS1000 sidescan sonar mosaic of a minibasin on the Louisiana upper continental slope.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-Apr-1999
    Ending_Date: 14-Apr-1999
    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 7531 x 14039 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: 15
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -93.000000
      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 1.999786
      Ordinates (y-coordinates) are specified to the nearest 1.922985
      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?
    Band_1
    Information unavailable from original metadata. (Source: Information unavailable from original metadata.)
    ObjectID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Entity_and_Attribute_Overview: There are no attributes associated with a GeoTIFF image.
    Entity_and_Attribute_Detail_Citation: 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)
    • David Twichell
    • VeeAnn Cross
    • William Danforth
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    David Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

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

Why was the data set created?

This GeoTIFF image is a 2 m enhanced version of a sidescan sonar mosaic collected using a Benthos SIS-1000 sidescan sonar system. The sonar mosaic has been enhanced and projected to UTM (zone 15) using the WGS 84 datum. This sidescan sonar mosaic was collected on the upper Louisiana continental slope in water depths less than 800 m, and covers an area of 329 km2. Results have been briefly summarized by Cooper et al. (1999).

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: 1999 (process 1 of 9)
    Sidescan sonar data were collected using a Benthos SIS-1000 sidescan sonar system and logged to a Triton/ELICS QMIPS data logging computer. Data sources produced in this process:
    • QMIPS data files
    Date: 1999 (process 2 of 9)
    The digital sidescan data were copied from the logging computer and then processed and mapped to provide proper geographic locations of features identified in the imagery. The first processing step was to edit the navigation to generate the best tow-vehicle navigation possible. A full description of the navigation processing steps is given by Foster and others (2000). The next set of processing steps included subsampling the raw sidescan data using a median filtering routine to suppress speckle noise and reduce file size, merging these image files with the edited navigation and then correcting for slant-range distortion and signal attenuation using XSonar (Danforth and others, 1991). After these steps the data were imported to the WHIPS software (Paskevich, 1992) and high- and low-pass filtering routines were used to reduce the noise associated with dropped sonar lines. Once the processing of individual strips was completed the imagery was mapped to its proper geographic location using techniques summarized by Paskevich (1996). The data were mapped in UTM (zone 15) using the WGS 84 datum at a 2-m pixel size. The navigation processing was done by David Foster, the XSonar processing by William Danforth, and the WHIPS processing and mapping by VeeAnn Cross. Person who carried out this activity:
    VeeAnn Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    (508) 548-8700 x 2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • QMIPS data files
    Data sources produced in this process:
    • WHIPS data files
    Date: 1999 (process 3 of 9)
    Non-overlapping swaths of sonar imagery were brought into the PCI remote sensing software and combined to create a composite digital mosaic. The techniques used to generate the composite digital sidescan mosaic are summarized by Paskevich (1992). This process step was completed by David Twichell Person who carried out this activity:
    David Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov
    Data sources used in this process:
    • WHIPS data files
    Data sources produced in this process:
    • Area2.pix
    Date: 1999 (process 4 of 9)
    A linear stretch was applied in PCI to the sidescan image to enhance the image. The data between values of 15 and 80 were spread across the full 8-bit range (0-255). High-backscatter (values near 255) in this image is white and low-backscatter (values near 0) is black. This step was completed by David Twichell. Person who carried out this activity:
    David Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov
    Data sources used in this process:
    • Area2.pix channel 1
    Data sources produced in this process:
    • Area2.pix channel 2
    Date: 06-May-2002 (process 5 of 9)
    The enhanced image mosaic was exported from the PCI 'pix' database as a GEOTIFF image with an associated "world" file. The completed mosaic has a 2-m pixel size. Person who carried out this activity:
    David Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov
    Data sources used in this process:
    • Area2.pix Channel 2
    Data sources produced in this process:
    • sis_enutm.tif
    Date: 16-Mar-2017 (process 6 of 9)
    Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). The link to the data in the Distribution_Information section had to be fixed. Attempted to modify http to https where appropriate. The link to the larger work citation had to be fixed. Online links were added to the cross-references. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 7 of 9)
    USGS Thesaurus keywords added to the keyword section. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 18-Nov-2019 (process 8 of 9)
    Crossref DOI link was added as the first link in the metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 08-Sep-2020 (process 9 of 9)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Foster, D.F., Twichell, D.C., Danforth, W.W., Irwin, B.J., Nichols, D.R., and O'Brien, T.F., 2000, Archive of SIS-1000 CHIRP subbottom data collected during USGS cruise GYRE 99002 Gulf of Mexico, 9-22 April, 1999: Open-File Report 99-586, U.S. Geological Survey, Reston, VA.

    Online Links:

    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: Sea Technology Jan., 1991.

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

    Online Links:

    Paskevich, V., 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, Reston, VA.

    Online Links:

    Cooper, A, Twichell, D, and Hart, P, 1999, A seismic-reflection investigation of gas hydrates and sea-floor features of the upper continental slope of the Garden Banks and Green Canyon regions, northern Gulf of Mexico: Report for cruise G1-99-GM (99002): Open-File Report 99-570, US Geological Survey, Reston, VA.

    Online Links:

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 ship was navigated with differential GPS, and location of the deep-towed sidescan vehicle was calculated in a variety of ways. In shallow water an acoustic ranging system was used in concert with vehicle depth and ship heading to compute vehicle location. In deeper water depths where the acoustic ranging system did not work, vehicle location was calculated in one of two ways. In some places the amount of wire out was used in place of the acoustic range. In other places, vehicle location was calculated by measuring the offset between features observed on the NOAA multibeam bathymetry and the tow vehicle echo sounder. This offset was measured at several points along each track and was used to compute vehicle navigation. Vehicle location was interpolated between the measured points. Comparison of features on the surface-towed seismic data with the same features on the deep-towed seismic data indicates that the offset mostly is less than 100 m.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    All sidescan data collected for the survey of this basin were included in the mosaic even though rough weather degraded the quality of part of the southernmost line.
  5. How consistent are the relationships among the observations, including topology?
    All these data were collected using the USGS SIS-1000 sidescan sonar. The data were all collected using a 1500 m total swath width. At the end of the first line, however, it was realized that the system was only scanning approximately 600 m rather than 750 m to each side of the tow vehicle, and the survey track lines were adjusted to account for this shorter swath width.

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:
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)
    David Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, MA
    USA

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@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?
    This image is available as a GeoTIFF image with an accompanying world file. To utilize this data, the user must have an image viewer, image processing or GIS software package capable of importing a GEOTIFF image.

Who wrote the metadata?

Dates:
Last modified: 16-Nov-2021
Metadata author:
U.S. Geological Survey
Attn: David Twichell
Oceanographer
384 Woods Hole Road
Woods Hole, MA
USA

(508) 548-8700 x2266 (voice)
(508) 457-2310 (FAX)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the metadata contact is no longer with the USGS or the email is otherwise invalid.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2005-1071/sis_enutmmeta.faq.html>
Generated by mp version 2.9.50 on Tue Nov 16 10:06:31 2021