Q2_SRELIEF.TIF - 6-m resolution gray-scale image of shaded-relief multibeam bathymetry in western Massachusetts Bay map Quadrangle 2

Metadata also available as - [Outline] - [Parseable text]

Frequently-anticipated questions:


What does this data set describe?

Title:
Q2_SRELIEF.TIF - 6-m resolution gray-scale image of shaded-relief multibeam bathymetry in western Massachusetts Bay map Quadrangle 2
Abstract:
The U.S. Geological Survey has conducted geologic mapping to characterize the sea floor offshore of Massachusetts. The mapping was carried out using a Simrad Subsea EM 1000 Multibeam Echo Sounder on the Frederick G. Creed on four cruises conducted between 1994 and 1998. The mapping was conducted in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and with support from the Canadian Hydrographic Service and the University of New Brunswick. The long-term goal of this mapping effort is to produce high-resolution geologic maps and a Geographic Information System (GIS) project that presents images and grids of bathymetry, shaded relief bathymetry, and backscatter intensity data from these surveys that will serve the needs of research, management and the public.
  1. How should this data set be cited?

    Butman, Bradford, and Danforth, William W. , 2007, Q2_SRELIEF.TIF - 6-m resolution gray-scale image of shaded-relief multibeam bathymetry in western Massachusetts Bay map Quadrangle 2: 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.

    Butman, Bradford, Valentine, Page C., Middleton, Tammie J., and Danforth, William W., 2007, A GIS Library of Multibeam Data for Massachusetts Bay and the Stellwagen Bank National Marine Sanctuary, Offshore of Boston, Massachusetts: Data Series 99, 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: -70.788907
    East_Bounding_Coordinate: -70.599983
    North_Bounding_Coordinate: 42.322212
    South_Bounding_Coordinate: 42.203333

  3. What does it look like?

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

    Beginning_Date: 1994
    Ending_Date: 1998
    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 2237 x 3934 x 1, type Pixel

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

      The map projection used is Mercator.

      Projection parameters:
      Standard_Parallel: 41.650000
      Longitude_of_Central_Meridian: -70.316667
      False_Easting: 0.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 6.000000
      Ordinates (y-coordinates) are specified to the nearest 6.000000
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:

  7. How does the data set describe geographic features?

    Band_1

    ObjectID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Value

    Count


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?

    U.S. Geological Survey
    c/o Bradford Butman
    Oceanographer
    384 Woods Hole Rd
    Woods Hole, MA 02543-1598
    USA

    (508) 548-8700 x2212 (voice)
    (508) 457-2309 (FAX)
    bbutman@usgs.gov

    Hours_of_Service: 8 a.m. - 5 p.m.


Why was the data set created?

This GeoTIFF (Tagged Image File Format) image shows shaded relief multibeam bathymetry in western Massachusetts Bay map Quadrangle 2 as grayscale at 6-m resolution.


How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, Multibeam bathymetric survey data collected by USGS in western Massachusetts Bay map quadrangle 2, 1994-1998.

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

    Date: Unknown (process 1 of 2)
    A suite of processing software (called SwathEd) (www.omg.unb.ca/~jhc/SwathEd.html), developed by the Ocean Mapping Group at the University of New Brunswick, Canada, was used to process and grid the multibeam bathymetric soundings and produce shaded-relief images. The metadata for the grids describes the processing steps applied to the navigation and bathymetric soundings. The following processing steps produced the image of shaded-relief bathymetry:
    1. Create a 6-m grid of the bathymetric soundings for Massachusetts Bay using the SwathEd routine weighgrid.
    Command line: weigh_grid -fresh_start -omg -tide -coeffs -mindep -2 -maxdep -800 -beam_mask -beam_weight -custom_weight EM1000_Weights -butter -power 2 -cutoff 12 -lambda 3 gridFile filename.merged
    2. Create a shaded relief image of the bathymetry using SwathEd routine addSUN (sun elevation of 45 degrees from 350, vertically exaggerating 4 times).
    Command line: addSUN -elev 45 -azi350 -vert_exag 4.0 gridFile.r4 filename.shade
    3. Use a two-point linear contrast stretch to enhance the shaded relief image:
    Command line: stretchacres -low 150 -high 200 -in filename.shade -out filename_shade.stretch
    4. Convert the contrast-stretched shaded relief image from SwathEd format to a tiff file using the netpbm utilities (<http://netpbm.sourceforge.net/>):
    Command line: rawtopgm -headerskip 1024 image_width image_height filename_shade.stretch | pnmtotiff -none - > filename.tif
    5. Create an ESRI world file (tfw) for the shaded relief tiff image for import to ArcView or ArcGIS. Copy bounding box and resolution information from the jview program output to the tfw file.
    Command line: jview filename_shade.stretch

    Person who carried out this activity:

    William Danforth
    U.S. Geological Survey
    Operational Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543-1598
    USA

    (508) 548-8700 x2274 (voice)
    (508) 457-2310 (FAX)
    bdanforth@usgs.gov

    Hours_of_Service: 8 a.m. to 5 p.m. EST
    Date: Feb-2007 (process 2 of 2)
    Image shifted 1/2 grid cell to northwest (using the ArcMap/Data Management Tools/Projections and Transformations/Raster/Shift tool) to correct for an error identified in the SwathEd gridding algorithm in 2007. Correct world file.

    Person who carried out this activity:

    William Danforth
    U.S. Geological Survey

    Data sources produced in this process:
    • q2_srelief.tif
    • q2_srelief.tfw

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

    Butman, Bradford, Hayes, Laura, Danforth, William W., and Valentine, Page C., 2003, Shaded relief and seafloor topography of Quadrangle 2 in western Massachusetts Bay offshore of Boston, Massachusetts: Geologic Investigations Series Map I-2732-B, 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?

    There are no attributes associated with a GeoTIFF image.

  2. How accurate are the geographic locations?

    These data were navigated with a Differential Global Positioning System (DGPS); they are accurate to +/- 3 meters, horizontally.

  3. How accurate are the heights or depths?

    These data have been corrected for vessel motion (roll, pitch, heave, yaw) and tidal offsets, and referenced to mean lower low water. The theoretical vertical resolution of the Simrad EM-1000 multibeam echosounder is 1% of water depth; roughly 30 - 50 cm within the study area. However, we found that the working vertical resolution of the system is roughly +/- 50 cm for water depths of 30 - 50 meters based on comparisons of grids from multi-year surveys of the same area.

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

    The multibeam bathymetric data, on which this image is based, were corrected for tidal elevation during the survey using sea level measured at the NOAA Boston tide gage. This assumes that the tidal elevation and phase are the same as Boston across the survey area. Further processing to correct for the spatial and temporal changes in tidal elevation across the survey area would improve the sounding data and may be undertaken at a later time.

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


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 2)

    Bradford Butman
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Road
    Woods Hole, Massachusetts 02543-1598
    USA

    (508) 548-8700 x2212 (voice)
    (508) 457-2309 (FAX)
    bbutman@usgs.gov

    Hours_of_Service: 8 a.m. to 5 p.m. EST
  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 these data have been used by the U.S. Geological Survey (USGS), U.S. Department of the Interior (DOI), no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. 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.


  1. Who distributes the data set? (Distributor 2 of 2)

    U.S. Geological Survey Information Services
    Box 25286 Denver Federal Center
    Denver, Colorado 80225-0046
    USA

    (303) 202-4700 (voice)
    (303) 202-4188 (FAX)

    Hours_of_Service: 8 a.m. to 5 p.m. Mountain Time
  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 these data have been used by the U.S. Geological Survey (USGS), U.S. Department of the Interior (DOI), no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. 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: 03-Apr-2007
Metadata author:
Bradford Butman
U.S. Geological Survey
Oceanographer
384 Woods Hole Road
Woods Hole, MA 02543-1598
USA

(508) 548-8700 x2212 (voice)
(508) 457-2310 (FAX)
bbutman@usgs.gov

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


Generated by mp version 2.9.1 on Wed Apr 04 08:00:02 2007