GeoTIFF image of shaded-relief bathymetry, colored by backscatter intensity, of the sea floor offshore of Fire Island Inlet, New York, in 1998 (3-m resolution, Mercator, WGS 84)

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Frequently anticipated questions:

What does this data set describe?

Title:
GeoTIFF image of shaded-relief bathymetry, colored by backscatter intensity, of the sea floor offshore of Fire Island Inlet, New York, in 1998 (3-m resolution, Mercator, WGS 84)
Abstract:
Surveys of the bathymetry and backscatter intensity of the sea floor south of Long Island, New York, were carried out in November 1998 using a Simrad EM1000 multibeam echosounder mounted on the Canadian Coast Guard ship Frederick G. Creed. The purpose of the multibeam echosounder surveys was to explore the bathymetry and backscatter intensity of the sea floor in several areas off the southern coast of Long Island along the 20-meter isobath. Survey areas offshore of Fire Island Inlet, Moriches Inlet, Shinnecock Inlet, and southwest of Montauk Point were about 1 kilometer (km) wide and 10 km long. The area was mapped by the U.S. Geological Survey with support from the Canadian Hydrographic Service and the University of New Brunswick.
Supplemental_Information:
Other data sets from this survey may be found in Butman and others (2016) (see larger work citation).
  1. How might this data set be cited?
    U.S. Geological Survey, 2016, GeoTIFF image of shaded-relief bathymetry, colored by backscatter intensity, of the sea floor offshore of Fire Island Inlet, New York, in 1998 (3-m resolution, Mercator, WGS 84): data release DOI:10.5066/F7Z899GG, 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.

    Butman, Bradford, Danforth, William W., John E. Hughes Clarke, Signell, Richard P., and Schwab, William C., 2016, Bathymetry and backscatter intensity of the sea floor south of Long Island, New York: data release DOI:10.5066/F7Z899GG, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.250000
    East_Bounding_Coordinate: -73.079999
    North_Bounding_Coordinate: 40.640000
    South_Bounding_Coordinate: 40.570008
  3. What does it look like?
    fire_srback3m_browse.jpg (JPEG)
    Image of shaded-relief bathymetry, colored by backscatter intensity, of the sea floor offshore of Fire Island Inlet, New York. File is located in the compressed zip file.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 06-Nov-1998
    Ending_Date: 07-Nov-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 2614 x 4839 x 1, type Pixel
    2. What coordinate system is used to represent geographic features?
      The map projection used is Mercator.
      Projection parameters:
      Standard_Parallel: 40.000000
      Longitude_of_Central_Meridian: -75.000000
      False_Easting: 0.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 3
      Ordinates (y-coordinates) are specified to the nearest 3
      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:
    In this GeoTIFF image, the backscatter intensity is combined with the bathymetry to display the distribution of intensity in relation to the bathymetry. The backscatter intensity is represented by a suite of eight colors ranging from blue (low intensity) to green to yellow to red (high intensity). These data are draped over a shaded-relief image created by vertically exaggerating the topography four times and then artificially illuminating the relief by a light source positioned 45 degrees above the horizon from 60 degrees. The resulting image displays light and dark intensities within each color band that result from a feature's position with respect to the light source. For example, east-facing slopes, receiving strong illumination, show as a light intensity within a color band, whereas west-facing slopes, being in shadow, show as a dark intensity within a color band. Image is 3-band, 24 bit R, G, B; (255,255,255) is no data.
    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?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Bradford Butman
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

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

Why was the data set created?

This data release makes multibeam echosounder data from the 1998 survey of the sea floor offshore of Fire Island Inlet, New York, available in digital form. The GeoTIFF image of shaded-relief bathymetry colored by backscatter intensity provides a visualization of both bathymetry and backscatter intensity. The shaded-relief image was created by vertically exaggerating the bathymetry 4 times and then artificially illuminating the relief by a light source positioned 45 degrees above the horizon from an azimuth of 60 degrees. The illumination from 60 degrees, approximately parallel to the survey lines, minimizes artifacts caused by small depth changes that may occur between lines. The backscatter intensity is represented by a suite of eight colors ranging from blue (low intensity) to green to yellow to red (high intensity).

How was the data set created?

  1. From what previous works were the data drawn?
    none (source 1 of 1)
    Service, Canadian Hydrographic, Danforth, William W., and John E. Hughes Clarke, Unpublished Material, raw multibeam data.

    Type_of_Source_Media: disc
    Source_Contribution:
    The multibeam data were collected with a Simrad EM1000 multibeam echosounder mounted on the starboard pontoon of the Canadian Coast Guard ship Frederick G. Creed. The multibeam system utilizes 60 electronically-aimed receive beams spaced at intervals of 2.5 degrees that insonify a strip of sea floor up to 7.5 times the water depth. The horizontal resolution of the beam on the sea floor is approximately 10 % of the water depth. Vertical resolution is approximately 1 % of the water depth. Data were collected along tracklines oriented approximately northeast-southwest, parallel to the local isobaths, and spaced about 100 m apart. The frequency of the sonar was 95 kHz. Sound velocity profiles were obtained and input into the Simrad processing system to correct for refraction. Navigation was by means of differential GPS. Operation of the Simrad EM1000 was carried out by hydrographers of the Canadian Hydrographic Service. The data were collected on Woods Hole Coastal and Marine Science Center field activity 1998-015-FA.
  2. How were the data generated, processed, and modified?
    Date: 2015 (process 1 of 7)
    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 backscatter intensity data, and to produce images. The metadata for the bathymetry grid (see link in larger work citation) describes the processing steps applied to the navigation and bathymetric soundings. The following processing steps produced the shaded-relief image of bathymetry colored by backscatter intensity for the Fire Island data set:
    1. Create a blank 8 bit map file: Command line: make_blank mosaic_file This command commences a dialog to enable an 8 bit image and input the map boundaries and resolution. The program also prompts for the projection type and parameters to be used creating the binary map file (custom Mercator projection, central longitude of -75 degrees, latitude of true scale 40 degrees north). Then the "blank" file is copied to two files required by the mosaic program: Command line: cp mosaic_file.blank mosaic_file.mos Command line: cp mosaic_file.blank mosaic_file.ran
    2. Create backscatter files that can be then mosaicked from the backscatter time series: Command line: getBeamPattern filename (prefix only) Command line: makess -pixel 1.0 -beam_patt beampatt filename (prefix only) output.ss Command line: glfill output.ss output.ss_fill (fills in data dropouts).
    3. Mosaic all the backscatter files created in the last step (for each output.ss_fill), and then use a two-point linear contrast stretch (0-254; 255 is no data) to enhance the backscatter image. Command line: mos2 -autoseam -maxazi 10 -maxdist 10 mosaic_file output.ss_fill Command line: stretchacres -low 170 -high 210 -in mosaic_file -out mosaic_file.stretch
    4. Create a shaded-relief image of the bathymetry using SwathEd routine addSUN (sun elevation of 45 degrees from 60, vertically exaggerating 4 times). Command line: addSUN -elev 45 -azi 60 -vert_exag 4.0 gridFile.r4 filename.shade
    5. Use a two-point linear contrast stretch (0-254; 255 is no data) to enhance the shaded-relief image: Command line: stretchacres -low 150 -high 200 -in filename.shade -out filename_shade.stretch
    6. Create an image of shaded-relief bathymetry, colored by backscatter intensity: Command line: mix_ci -c mosaic_file.stretch -i filename_shade.stretch -m mosaic_file.pseudo Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    wdanforth@usgs.gov
    Date: 2015 (process 2 of 7)
    Create a TIFF from the pseudocolored backscatter mosaic file using the netpbm utilities (http://netpbm.sourceforge.net/): Command line: rawtopgm -headerskip 1024 image_width image_height mosaic_file.pseudo | pnmtoTIFF -none - > mosaic_pseudo.tif Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2274 (voice)
    wdanforth@usgs.gov
    Date: 2015 (process 3 of 7)
    Create a TIFF world file (tfw) for the pseudocolored backscatter intensity image for use in ArcGIS. Copy bounding box and resolution information from the jview program output to the .tfw file. Command line: jview mosaic_file.pseudo Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2274 (voice)
    wdanforth@usgs.gov
    Date: 2015 (process 4 of 7)
    Import image into Photoshop and convert from an 8-bit image to a 3-band 24-bit RGB image. This improves the quality of the image when viewed in ArcMAP at large scale. Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2274 (voice)
    wdanforth@usgs.gov
    Date: 2016 (process 5 of 7)
    Create GeoTIFF image using the Define Projection Tool in Data Management Tools, Projections and Transformations in ArcToolbox 9.3. Custom Mercator projection, central meridian of -75.0 degrees, latitude of true scale 40.0 degrees north, false easting 0.0, false northing 0.0; Geographic Coordinate System WGS 1984. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Bradford Butman
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2212 (voice)
    bbutman@usgs.gov
    Date: 20-Jul-2018 (process 6 of 7)
    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: 10-Aug-2020 (process 7 of 7)
    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?
    Schwab, W.C., Thieler, E.R., Denny, J.F., and Danforth, W.W., 2000, Seafloor sediment distribution off southern Long Island, New York: Open-File Report 00-243, 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?
    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?
  4. Where are the gaps in the data? What is missing?
    This image contains all data collected in the multibeam survey offshore of Fire Island Inlet, New York, in 1998. There are a few gaps in the image due to incomplete coverage by the multibeam system. Other data sets collected offshore of Long Island, New York, on WHCMSC field activity 1998-015-FA may be found in Butman and others (2016) (see larger work citation).
  5. How consistent are the relationships among the observations, including topology?
    Some features in the multibeam data are artifacts of data collection and environmental conditions. They include small highs and lows and unnatural-looking features, and patterns oriented parallel or perpendicular to survey tracklines. The orientation of the tracklines is sometimes identified by parallel stripes in the image. During data acquisition, the electrically erasable programmable read only memory (EEPROM) within the transceiver that controls the beam launch angles was programmed with incorrect parameters for the outer ten beams on the port and starboard sides. This caused depth soundings to be deeper for these outer beams by approximately 0.1 m; these deeper soundings are not corrected. The Long Island surveys were assigned a block of line numbers beginning with 3000.

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 These data are not to be used for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center
    Denver, CO
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? fire_srback3m.zip: contains fire_srback3m.tif, fire_srback3m.tfw, and associated FGDC-compliant metadata (CSDGM format).
  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?
    The GeoTIFF image of shaded-relief bathymetry colored by backscatter intensity is compressed into a WinZip (version 14) file (fire_srback3m.zip). To use these data, the user must have software capable of uncompressing the zip file and ArcGIS or another GIS application package capable of viewing the data.

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: Bradford Butman
384 Woods Hole Road
Woods Hole, MA

508-548-8700 x2212 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_F7Z899GG/fire_srback3m_meta.faq.html>
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