DH_USGS_backscatter1m: Composite sidescan-sonar mosaic collected by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull (UTM Zone 19N GeoTIFF)

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Frequently-anticipated questions:

What does this data set describe?

Title:
DH_USGS_backscatter1m: Composite sidescan-sonar mosaic collected by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull (UTM Zone 19N GeoTIFF)
Abstract:
These data were collected under a cooperative agreement with the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Science Center (WHSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of sea-floor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters (5-30 m deep) of Massachusetts between the New Hampshire border and Cape Cod Bay. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (<http://woodshole.er.usgs.gov/project-pages/coastal_mass/html/current_map.html>). This spatial dataset is from the study area located between Duxbury and Hull Massachusetts, and consists of high-resolution geophysics (bathymetry, backscatter intensity, and seismic reflection) and ground validation (sediment samples, video tracklines and bottom photographs). The data were collected during four separate surveys conducted between 2003 and 2007 (NOAA survey H10993 in 2003, USGS-WHSC survey 06012 in 2006, and USGS-WHSC surveys 07001 and 07003 in 2007) and cover more than 200 square kilometers of the inner continental shelf.
  1. How should this data set be cited?

    U.S. Geological Survey, 2010, DH_USGS_backscatter1m: Composite sidescan-sonar mosaic collected by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull (UTM Zone 19N GeoTIFF): Open-File Report 2009-1072, 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.

    Barnhardt, Walter A. , Ackerman, Seth D. , Andrews, Brian D. , and Baldwin, Wayne E. , 2010, Geophysical and Sampling Data from the Inner Continental Shelf: Duxbury to Hull, Massachusetts.: Open-File Report 2009-1072, 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: -70.833187
    East_Bounding_Coordinate: -70.590966
    North_Bounding_Coordinate: 42.348435
    South_Bounding_Coordinate: 42.074860

  3. What does it look like?

    <https://pubs.usgs.gov/of/2009/1072/GIS/browse_jpg/big/DH_USGS_backscatter1m.jpg> (JPEG)
    grey scale image of sidescan-sonar mosaic

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

    Beginning_Date: 04-Aug-2006; 20070422
    Ending_Date: 20-Aug-2006; 20070502
    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 30000 x 19400 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: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      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) with the data range 0-254. 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 255 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?

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

Why was the data set created?

This GeoTIFF (Tagged Image File Format) contains approximately 186 square-km of Klein 3000 sidescan-sonar data that were collected by the U.S. Geological Survey during two surveys (USGS surveys 06012 and 07001) offshore of Massachusetts, between Duxbury and Hull. These data are used to define the sea-floor morphology as part of the Massachusetts Sea-floor Mapping Project.

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:
    Data acquisition at sea: Sidescan sonar data were collected with a Klein 3000 dual frequency (132/445 kHz) sidescan sonar towfish on the R/V Megan T. Miller (06012) and the R/V Rafael (07001). During survey 06012 the sonar was towed from the stern A-frame of the R/V Megan T. Miller; a cable counter measured the towfish layback and automatically adjusted the layback parameter in the acquisition software (SonarPro version 9.6). During survey 07001, the sonar was towed from the port side aft on the R/V Rafael; layback was fixed and SonarPro version 10.0 was used on the acquisition computer. Tracklines are generally spaced 100m apart (200m in the northern area where the USGS data overlaps with NOAA multibeam echo-sounder data). Data were acquired roughly parallel to the shoreline at an average speed of 5 knots.

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

    Date: 2006 (process 1 of 4)
    Within XSonar Software (version: 1.1) a median filtering routine (4 pixels across track by 3 pixels along track) was applied to the raw sidescan-sonar data (XTF) to remove speckle noise. The data were further processed to correct for fish altitude, slant and beam artifacts, and then merged with the navigation (Danforth, 1997). Adjacent sidescan sonar lines were mapped out separately from XSonar into north-heading and south-heading sonar mosaics at 1 meter/pixel resolution. Sidescan areas were defined within the survey trackline planning scheme such that the sonar images mapped in XSonar would have the same line orientation and keep the working mosaics to a manageable filesize.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2315 (voice)
    (508) 457-2310 (FAX)
    sackerman@usgs.gov

    Date: 2007 (process 2 of 4)
    A PCI Geomatica (version: 10.0.3) project was created for each subarea of the Duxbury to Hull survey area. The north and south-heading working mosaics were imported into PCI Geomatica to be digitally mosaicked together using PCI's OrthoEngine and procedures described in Paskevich (1996) and Paskevich and others (Unpublished, 2007). The mosaicking process produces an enhanced, geographically correct, sidescan-sonar mosaic with 1 meter/pixel resolution. The subareas were tone-adjusted within PCI's OrthoEngine mosaicking tools (to account for tonal-variation as a result of changes to the acquisition parameters or variations introduced as a result of processing); then mosaicked together into a composite backscatter image for the entire survey area. The composite mosaic was exported as a GeoTIFF image.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2315 (voice)
    (508) 457-2310 (FAX)
    sackerman@usgs.gov

    Date: 2008 (process 3 of 4)
    Most of the NODATA area in the GeoTIFF image (outside the survey bounds) have a backscatter pixel value of 255. But as a result of the mosaicking process, some areas of NODATA have a backscatter pixel value of 254. Using Adobe Photoshop CS2 (version 9.0.2), all of the NODATA areas were selected and made to have a single NODATA value, such that all NODATA in the final mosaic will have a pixel value of 255. All backscatter data within the survey area have a value of <255, although some small data gaps (NODATA) do occur within the survey area as well. A two-pixel median filter was applied to TIFF image to eliminate speckle noise in the final mosaic and small gaps of < 1 meter.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2315 (voice)
    (508) 457-2310 (FAX)
    sackerman@usgs.gov

    Date: 2009 (process 4 of 4)
    A TIFF World File (TFW) was created using Mentor Software GeoTiffExaminer (no version) to define the spatial extent of the TIFF image. GeoTiffExaminer was also used to transfer the spatial information to the TIFF, creating a GeoTIFF image

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2315 (voice)
    (508) 457-2310 (FAX)
    sackerman@usgs.gov

    Data sources used in this process:
    • DH_USGS_backscatter1m.tfw

    Data sources produced in this process:

    • DH_USGS_backscatter1m.tif

  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: Sea Technology Jan. 1991, Sea Technology, Arlington, VA.

    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, Woods Hole Science Center, Woods Hole, MA.

    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, Woods Hole Science Center, Woods Hole, MA.

    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, Woods Hole Science Center, Woods Hole, MA.

    Paskevich, Valerie, Denny, Jane, and Ackerman, Seth, Unpublished, The Ultimate Guide to Mosaicking Sidescan Sonar Data in PCI Geomatica v.10.0.3: none none, Unpublished, U.S. Geological Survey, Woods Hole Science Center, Woods Hole, MA.

    Barnhardt, Walter A. , Andrews, Brian D. , and Butman, Bradford, 2006, High-Resolution Mapping of the Inner Continental Shelf: Nahant to Gloucester, Massachusetts: Open-File Report 2005-1293, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Ackerman, Seth D. , Butman, Bradford, Barnhardt, Walter A. , Danforth, William W. , and Crocker, James M. , 2006, High-Resolution Geologic Mapping of the Inner Continental Shelf: Boston Harbor and Approaches, Massachusetts: Open-File Report 2006-1008, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Barnhardt, Walter A. , Andrews, Brian D. , Ackerman, Seth D. , Baldwin, Wayne E. , and Hein, Christopher J. , 2009, High-Resolution Geological Mapping of the Inner Continental Shelf: Cape Ann to Salisbury Beach, Massachusetts: Open-File Report 2007-1373, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    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 data range (0-255). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values).

  2. How accurate are the geographic locations?

    Field activity 06012: The Klein 3000 was towed from the stern A-frame of the R/V Megan T. Miller. Position data were provided by the Z-Surveyor Extreme for real-time kinematic (RTK) navigation and recorded to the raw data files (XTF) via SonarPro (version 9.6) on the sonar acquisition computer. During some portions of the survey, technical difficulties caused the GPS systems to malfunction; in some instances the acquisition systems fell back on the RTK Float or the autonomous GPS navigation; but in some cases surveying was halted until a reliable GPS signal could be achieved. Layback positions, which account for the linear distance between the shipboard RTK-GPS receiver and the towed sonar vehicle were measured by a cable counter on the winch that was used to deploy the sidescan-sonar towfish. Layback offsets were directly applied into the acquisition software so the navigation recorded in the XTF data reflect the position including the layback offset. A conservative estimate of positional accuracy is estimated to be 10 m although when the system was recording RTK navigation the positional accuracy is likely <1 m as RTK-GPS provides horizontal positional accuracies on the decimeter scale. Positional uncertainty arises because 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.

    Field activity 07001: The Klein 3000 was towed from the port side aft on the R/V Rafael. Position data were provided by the Ashtech Extreme for real-time kinematic (RTK) navigation and recorded to the raw data files (XTF) via SonarPro (version 10.0) on the sonar acquisition computer. A conservative estimate of positional accuracy is estimated to be 10 m although when the system was recording RTK navigation the positional accuracy is likely <1 m as RTK-GPS provides horizontal positional accuracies on the decimeter scale. Layback was fixed and figured into the navigation during acquisition.

  3. How accurate are the heights or depths?

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

    Only the subset of sidescan-sonar backscatter data collected during field activities 06012 and 07001 that are within the study area between Duxbury and Hull have been included in this spatial dataset. Approximately 125 square-km of additional sidescan-sonar backscatter data were collected south of Brant Rock, Massachusetts during these field activities will be published in a subsequent data release focused on Cape Cod Bay. Some sections of sonar data with excess noise were clipped during processing.

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

    This image represents mainline sidescan sonar data; no crossline data were included in this image. Gaps may occur along-track and between adjacent lines.

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)

    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@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 U.S. Geological Survey 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 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. A free spatial data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 29-Oct-2009
Metadata author:
Seth Ackerman
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543-1598
USA

508-548-8700 x2315 (voice)
508-457-2310 (FAX)
sackerman@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 Fri Feb 19 21:04:11 2010