One meter mosaic of acoustic backscatter data acquired using an EdgeTech 4200 sidescan sonar within Little Egg Harbor (Barnegat Bay) New Jersey by the U.S. Geological Survey in 2013 (GeoTIFF image, UTM 18N, WGS 84)

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Frequently anticipated questions:


What does this data set describe?

Title:
One meter mosaic of acoustic backscatter data acquired using an EdgeTech 4200 sidescan sonar within Little Egg Harbor (Barnegat Bay) New Jersey by the U.S. Geological Survey in 2013 (GeoTIFF image, UTM 18N, WGS 84)
Abstract:
In 2011, the U.S. Geological Survey (USGS) in partnership with the New Jersey Department of Environmental Protection began a multidisciplinary research project to better understand the water quality in Barnegat Bay, New Jersey. This back-barrier estuary is flushed by only three inlets and is experiencing degraded water quality, algal blooms, loss of seagrass, and increases in oxygen stress, macro algae, stinging nettles, and brown tide. The scale of the estuary and the scope of the problems within it necessitate a multidisciplinary approach that includes establishing the regional geology, its physical characteristics, and modeling how the estuary's morphology interacts to affect its water quality. Scientists from USGS Coastal and Marine Geology Program offices in Woods Hole, Massachusetts, and St. Petersburg, Florida, began mapping the seafloor of the Barnegat Bay-Little Egg Harbor estuary in November 2011 and completed in September 2013. With funding from the New Jersey Department of Environmental Protection and logistical support from the USGS New Jersey Water Science Center, they collected data with a suite of geophysical tools, including swath bathymetric sonar for measuring seafloor depth, a sidescan sonar for collecting acoustic-backscatter data (which provides information about seafloor texture and sediment type), subbottom profiler for imaging sediment layers beneath the floor of the estuary, and sediment samples with bottom photographs for ground validation of the acoustic data. More information about the individual surveys conducted as part of the Barnegat Bay Project can be found on the Woods Hole Coastal and Marine Science Center Field activity webpages: 2011-041-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2011-041-FA 2012-003-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2012-003-FA 2013-014-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2013-014-FA 2013-030-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2013-030-FA
  1. How might this data set be cited?
    U.S. Geological Survey, 2015, One meter mosaic of acoustic backscatter data acquired using an EdgeTech 4200 sidescan sonar within Little Egg Harbor (Barnegat Bay) New Jersey by the U.S. Geological Survey in 2013 (GeoTIFF image, UTM 18N, WGS 84): Data Series 937, 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.

    Andrews, Brian D., Miselis, Jennifer L., Danforth, William W., Irwin, Barry J., Worley, Charles R., Bergeron, Emile M., and Blackwood, Dann S., 2015, Marine geophysical data collected in a shallow back-barrier estuary: Barnegat Bay, New Jersey: Data Series 937, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -74.316615
    East_Bounding_Coordinate: -74.246329
    North_Bounding_Coordinate: 39.608236
    South_Bounding_Coordinate: 39.567260
  3. What does it look like?
    LittleEggHbrBS_1m.jpg (JPEG)
    Grayscale thumbnail image of backscatter collected within Little Egg Harbor, NJ. The file is located in the compressed zip file.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 11-Sep-2013
    Ending_Date: 16-Sep-2013
    Currentness_Reference:
    ground condition of individual surveys during backscatter collection:20130911-20130916.
  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 4500 x 6000 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: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      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 (DN) normalized to an 8-bit data range (0-255) with the data range 1-255 (no data value is 0). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). The data mean DN value for this mosaic is 11.4 with a standard deviation of 13.3.
    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)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
    Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  3. To whom should users address questions about the data?
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

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

Why was the data set created?

This mosaic of acoustic backscatter will be used to interpret the sediment composition of Little Egg Harbor and assist in understanding the regional geology of Barnegat Bay.

How was the data set created?

  1. From what previous works were the data drawn?
    raw EdgeTech files (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, Raw EdgeTech files.

    Type_of_Source_Media: disc
    Source_Contribution:
    During USGS Survey 2013-030-FA a EdgeTech sidescan sonar operating at a frequency of 100 and 400 kHz was used. The sonar tow-fish was towed from the port side of the R/V Rafael approximately 1.5 m astern.
  2. How were the data generated, processed, and modified?
    Date: Sep-2013 (process 1 of 6)
    Step 1: Convert raw sidescan files to XSonar format. During 2011-041-FA sidescan sonar files were collected using a Klein 3000 sidescan sonar and recorded using the eXtended Triton Format (xtf). The remaining three surveys (2012-003-FA, 2013-014-FA, and 2013-030-FA) used an EdgeTech 4200 sidescan sonar and recorded files using the Jason Special Format (jsf). The first step in processing backscatter data is the same for both raw data types. Using XSonar/ShowImage software (v. 2.0) (Danforth 1997) the raw line files were converted (Demultiplexed) to XSonar format using a 50-m range (100 meter swath) and navigation was extracted at intervals of 30 seconds. During this conversion an across track filter of 4 and along track filter of 3 pixels were used to smooth the backscatter values. In addition, a normalization of 4095 (out of 16-bit range of 65,536) was applied to produce a *.d file for each input line file. During the demultiplex operation a static value of 2-meters was used to search for the first bottom return. Next the slant range correction routine was run on each *.d file to produce a corrected *.ds file. Each file was reviewed in ShowImage (v. 1.0) to ensure that the bottom picks and slant range were correct and manually adjusted if required. Next a beam pattern correction was applied to each .ds file to produce a *.dsb file. The beam pattern corrections used a ping overlap of 75 for each 150 lines (scans) of the sonar. A weighted tone adjustment was also applied during this step. The final step in XSonar produces separate raster (.*.ras) files at 1.0 meter resolution in UTM Zone 18 WGS 84 coordinates for even and odd lines. Person who carried out this activity:
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
    Date: Sep-2013 (process 2 of 6)
    Step 2: XSonar to TIFF conversion: Each *.ras file was converted to a raw raster file (*.raw) at a resolution of 1-m per pixel. The 80-byte header for each *ras raster file was removed and the images were converted to a raster (.raw) file with the command: dd if=filename.ras of=filename.raw bs=80 skip=1. The resulting rasters (.raw) were converted to a TIFF using Adobe Photoshop (ver. 10.0.1). Person who carried out this activity:
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
    Date: 24-Mar-2014 (process 3 of 6)
    Step 3: Create Mosaic: A PCI Geomatica (v. 10.1) project was created using the "mosaic only option" The mosaics of odd and even lines were imported into PCI Geomatica to be digitally mosaicked together using PCI's OrthoEngine and procedures described in Paskevich 1996. The mosaicking process produces an enhanced, geographically correct, sidescan-sonar mosaic with 1 meter/pixel resolution. Mosaics were created for each Julian Day and then mosaicked into a master mosaic for the entire survey. The composite mosaic was exported as a GeoTIFF image. Person who carried out this activity:
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
    Date: 20-Jul-2018 (process 4 of 6)
    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: 15-Nov-2019 (process 5 of 6)
    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 6 of 6)
    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?
    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, Reston, VA.

    Online Links:

    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, Reston, VA.

    Online Links:


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

  1. How well have the observations been checked?
    Image pixel values contain acoustic reflectivity values normalized to an 8-bit range (0-255). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). No data value = 0.
  2. How accurate are the geographic locations?
    Navigation for these data were recorded using a Hemisphere DPGS receiver located on top of the cabin house of the R/V Rafael. Offsets between the antenna and sidescan towfish (layback) were measured and recorded in the Klein SonarPro acquisition software (v. 10.0) and SonarWiz (v. 7.02). The DGPS is accurate to within 1-2 meters. A conservative estimate of the horizontal accuracy of this backscatter mosaic is 2-3 meters.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This mosaic includes data collected during USGS Field Activity 2013-030-FA. A separate mosaic (BarnBayBS_1m.tif) covers the northern (main) part of Barnegat Bay collected during 2011-014-FA, 2012-003-FA and 2013-013-FA. This mosaic does not include all acoustic backscatter collected using the EdgeTech 4200 sidescan sonars. Data collected along some transit and seismic tie lines, and other lines of poor quality are not included in this mosaic.
  5. How consistent are the relationships among the observations, including topology?
    Acoustic data were collected using an EdgeTech 4200 dual frequency (100/400 kHz) sidescan sonar USGS Survey 2013-030-FA. Only the low frequency data (100 kHz) were processed and included in this mosaic.

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
  1. Who distributes the data set? (Distributor 1 of 1)
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    bandrews@usgs.gov
  2. What's the catalog number I need to order this data set? LittleEggHbrBS_1m.zip contains: LittleEggHbrBS_1m.tiff, LittleEggHbrBS_1m.jpg browse graphic, and the associated FGDC compliant metadata. To display this mosaic along with the other two in this publication, use the "BarnegatBay Backscatter.lyr" located in the BarnBayBS_1m.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?
    • Availability in digital form:
      Data format: WinZip (V. 14) file contains a GeoTIFF image and associated metadata of sidescan-sonar data collected in Little Egg Harbor (Barnegat Bay), NJ and associated metadata. in format GeoTIFF (version PCI Geomatica 10.1) GeoTIFF image Size: 9.5
      Network links: http://pubs.usgs.gov/ds/0937/downloads/raster/backscatter/LittleEggHbrBS_1m.zip
    • Cost to order the data: none

  5. What hardware or software do I need in order to use the data set?
    This Zip file contains a compressed GeoTIFF image and world file. The user must have software capable of uncompressing the zip file and viewing a GeoTIFF image.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
Brian Andrews
U.S. Geological Survey
Geographer
384 Woods Hole Rd.
Woods Hole, MA
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)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/data_series/DS-937/LittleEggHbrBS_1m.faq.html>
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