1-meter resolution sidescan-sonar mosaic image collected by the U.S. Geological Survey along the Delmarva Peninsula, MD and VA in 2015 (8-bit GeoTIFF, UTM Zone 18N, WGS 84)

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Frequently anticipated questions:


What does this data set describe?

Title:
1-meter resolution sidescan-sonar mosaic image collected by the U.S. Geological Survey along the Delmarva Peninsula, MD and VA in 2015 (8-bit GeoTIFF, UTM Zone 18N, WGS 84)
Abstract:
The Delmarva Peninsula is a 220-kilometer-long headland, spit, and barrier island complex that was significantly affected by Hurricane Sandy in the fall of 2012. The U.S. Geological Surveys conducted cruises during the summers of 2014 and 2015 to map the inner continental shelf of the Delmarva Peninsula using geophysical and sampling techniques to define the geologic framework that governs coastal system evolution at storm-event and longer timescales. Geophysical data collected during the cruises include swath bathymetric, sidescan sonar, chirp and boomer seismic reflection profiles, grab sample and bottom photograph data. More information about the USGS survey conducted as part of the Hurricane Sandy Response-- Geologic Framework and Coastal Vulnerability Study can be found at the project website or on the WHCMSC Field Activity Web pages: https://woodshole.er.usgs.gov/project-pages/delmarva/, https://cmgds.marine.usgs.gov/fan_info.php?fan=2014-002-FA and https://cmgds.marine.usgs.gov/fan_info.php?fan=2015-001-FA. Data collected during the 2014 survey can be obtained here: https://doi.org/10.5066/F7MW2F60
Supplemental_Information:
The 1-m backscatter mosaic did not need to be updated for the 2nd edition data release and has not changed since the 1st edition.
  1. How might this data set be cited?
    U.S. Geological Survey, 2015, 1-meter resolution sidescan-sonar mosaic image collected by the U.S. Geological Survey along the Delmarva Peninsula, MD and VA in 2015 (8-bit GeoTIFF, UTM Zone 18N, WGS 84): data release DOI:10.5066/F7P55KK3, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Sweeney, Edward M., Pendleton, Elizabeth A., Ackerman, Seth D., Andrews, Brian D., Baldwin, Wayne E., Danforth, William W., Foster, David S., Thieler, E. Robert, and Brothers, Laura L., 2016, High-resolution geophysical data collected along the Delmarva Peninsula 2015, U.S. Geological Survey Field Activity 2015-001-FA: data release DOI:10.5066/F7P55KK3, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.908519
    East_Bounding_Coordinate: -75.061073
    North_Bounding_Coordinate: 37.854775
    South_Bounding_Coordinate: 36.995183
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data/field-activity-data/2015-001-FA/data/backscatter/2015-001-FA_sss_browse.jpg (JPEG)
    Thumbnail image of regional sidescan sonar mosaic for Delmarva Peninsula.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 17-Jun-2015
    Ending_Date: 14-Jul-2015Currentness_Reference:
    ground condition; data were not collected on 20150628 (transition between Legs 1 and 2 of the survey)
  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 94989 x 74493 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: 18N
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      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. Pixel values for the GeoTIFF have a possible 8-bit pixel range of 0 to 255. However, the acoustic reflectivity data range from 1 to 237, with the NO DATA value at 238 (pixel values 0 and 239 to 255 fall outside the range of the data values). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). The background color is set to 238 and can be turned off without removing data values.
    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)
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Edward M. Sweeney
    U.S. Geological Survey
    Physical Scientist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2256 (voice)
    508-457-2310 (FAX)
    emsweeney@usgs.gov

Why was the data set created?

This 1-m backscatter mosaic was created from 100 kHz Edgetech sidescan sonar data. Backscatter mosaic images are useful geophysical datasets for geologic framework studies. These data can be used in conjunction with other geophysical and sample data to identify sea-floor morphology and sediment texture.

How was the data set created?

  1. From what previous works were the data drawn?
    raw backscatter (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw interferometric data in .sxr format.

    Type_of_Source_Media: disc
    Source_Contribution:
    Sidescan sonar data were collected with an Edgetech 4200 dual frequency (100/410 kHz) frequency modulated sidescan-sonar towfish on the M/V Scarlet Isablella. The sonar was towed from the stern A-frame of the vessel. A 3PS digital block cable counter was used to measure the amount of tow cable deployed, and cable out values were transmitted via serial connection to the Edgetech Discover (version 34.0.1.106) acquisition software (lines L40F1 to L47F1) and SonarWiz software (version 6.01.0009) (lines L47F3 to L183-20150714_134804) on the sonar acquisition computer for layback calculation. Tracklines are generally spaced 200m apart.
  2. How were the data generated, processed, and modified?
    Date: 14-Jul-2015 (process 1 of 3)
    Raw XTF format Edgetech sidescan data (100 kHz) were imported into SonarWiz version 6.01.0009 software on the M/V Scarlet Isabella for preliminary shipboard processing. Each line received a bottom tracking correction to remove the water column at nadir. SonarWiz has an automatic bottom-tracking algorithm that generally performs well in most coastal settings. Auto tracking parameters for this survey were set to a blanking value of 4; a duration value of 2; and a threshold of 19 with line smoothing turned on. Some lines required further adjustment to the auto bottom tracking delineation, which can be addressed by manually editing the altitude line in SonarWiz. There was a 0.3 m additional altitude offset applied to the bottom tracking, in order to minimize nadir beam pattern noise in parts of the mosaic. The only gain function applied in SonarWiz during shipboard processing was an empirical gain normalization function (EGN). The Overlap Mode in the SonarWiz project was set to Cover Up, which displays backscatter data from the overlying swath line only and does not make adjustments (average, root mean square, etc.) between data in overlapping swaths. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Edward M. Sweeney
    Physical Scientist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2256 (voice)
    508-457-2310 (FAX)
    emsweeney@usgs.gov
    Date: 04-Nov-2015 (process 2 of 3)
    The sidescan sonar mosaic was split into 2 separate images (north and south survey areas) and exported from SonarWiz version 6.01.0026 as 8-bit GeoTIFFs (UTM Zone 18N, WGS 84) at 1-m resolution. High backscatter values are shown by light tones and low backscatter values are shown by dark tones in the imagery. The 2 GeoTIFF images were opened in ArcMap version 10.3.1 and mosaicked into 1 GeoTIFF file using the MOSAIC TO NEW RASTER tool. A world file with the same prefix file name and .tfw extension was created in ArcMap version 10.3.1 using EXPORT RASTER WORLD FILE tool. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Edward M. Sweeney
    Physical Scientist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2256 (voice)
    508-457-2310 (FAX)
    emsweeney@usgs.gov
    Date: 19-Apr-2017 (process 3 of 3)
    The online links to the data were updated to reflect the new server hosting the data. Additionally, other small edits could be made to the metadata, such as modifying http to https where appropriate. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. 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?
    Pendleton, Elizabeth A., Ackerman, Seth D., Baldwin, Wayne E., Danforth, William W., Foster, David S., Thieler, E. Robert, and Brothers, Laura L., 2015, High-resolution geophysical data collected along the Delmarva Peninsula 2014, U.S. Geological Survey Field Activity 2014-002-FA: data release DOI:10.5066/F7MW2F60, U.S. 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?
    During Field activity 2015-001-FA, the Edgetech 4200 was towed from the stern A-frame of the M/V Scarlett Isabella. Position data were acquired using a Wide Area Augmentation System (WAAS) enabled Hemisphere Differential Global Positioning System (DGPS) receiver. Horizontal position solutions were recorded to the raw data files (JSF and XTF) via Edgetech Discover version 34.0.1.106 acquisition software (lines L40F1 to L47F1) and SonarWiz software version 6.01.0009 (lines L47F3 to L183-20150714_134804) on the sonar acquisition computer. The GPS antenna was mounted on the forward port side of the acquisition lab van. All GPS data during this survey were referenced to the WGS 84 horizontal datum. The horizontal offsets between the GPS antenna and the sheave on the A-frame were measured prior to the survey (x: +3.76 m; y: -12.76 m; z: 1.0 m). The side-scan tow cable was deployed through a 3PS digital block cable counter attached to the A-frame. Real-time cable-out measurements were transmitted via serial connection to the Discover and SonarWiz acquisition software, which calculated tow-fish layback. All horizontal offsets were applied in the acquisition software so the navigation recorded in the JSF and XTF data reflect the position including the layback offset. The layback calculations do not account for fish motion behind the vessel, which is caused by sea state and vessel speed induced changes in the angle and scope of the tow cable. DGPS horizontal positional accuracy is estimated to be within 3-5 m; WAAS enable GPS is estimated to be less than 2 m. Taking the additional fish motion and cable movement into account, as well as the mosaicking process, the positional accuracy for this dataset is estimated to be within 20 m.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Cross lines (L123-20150704_122457-CH12, L123-20150704_132335-CH12, L125-20150704_132802-CH12, L143-20150705_194038-CH12) are not included in this sidescan sonar mosaic. However, all of the other Edgetech data collected during field activity 2015-001-FA are included in this mosaic and were processed with SonarWiz versions 6.01.0009 (onboard) and 6.01.0026 (post-survey). Edgetech data were not collected during the entire survey. While regional seismic-reflection profile lines were being acquired with an S-Boom system between 20150610 and 20150618, the Edgetech 4200 remained on deck to avoid signal crosstalk and instrument entanglement.
  5. How consistent are the relationships among the observations, including topology?
    These sidescan sonar data were collected at 200 m line spacing to ensure 100 percent backscatter coverage. The M/V Scarlet Isabella can only survey in water depths greater than 8 m, so there are gaps in the mosaics where the vessel had to avoid crossing shoals. These gaps were planned with breaks in tracklines or maneuvers around the shoals. Most of the data were acquired roughly parallel to the orientation of the Delmarva Peninsula at an average speed of 5 knots. Line numbering in the sidescan sonar data begins with L40F1, which corresponds to the survey line where sidescan data collection began after the multi-channel seismic reflection profiling survey.

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 as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    Edward M. Sweeney
    U.S. Geological Survey
    Physical Scientist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2256 (voice)
    508-457-2310 (FAX)
    emsweeney@usgs.gov
  2. What's the catalog number I need to order this data set? USGS data release 2015-001-FA backscatter mosaic from the Delmarva Peninsula area (2015-001-FA_sss.zip). The zip file contains the following a GeoTIFF image: 2015-001-FA_sss.tif, which has a TIFF world file, with the same image prefix name and a .tfw extension. A browse graphic (2015-001-FA_sss_browse.jpg) and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata files (2015-001-FA_sss.xml) in four standard formats are also included in the zip file.
  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 GeoTIFF image files and associated metadata files. To utilize these data, the user must have software capable of viewing GeoTIFF image files.

Who wrote the metadata?

Dates:
Last modified: 19-Apr-2017
Metadata author:
Edward M. Sweeney
U.S. Geological Survey
Physical Scientist
384 Woods Hole Road
Woods Hole, Massachusetts
USA

508-548-8700 x2256 (voice)
508-457-2310 (FAX)
emsweeney@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.9.36 on Wed Apr 19 13:05:38 2017