all_back.faq.html

Metadata also available as - [Outline]

Frequently-anticipated questions:

What does this data set describe

Title:

all_back.txt - Sidescan sonar backscatter image (for the entier study area)
Abstract:

The sonar amplitude image of the nearshore sea floor (0 to 80 m water depths)
of the Elwha River mouth area was mosaicked from data collected
in 2005. A 234 kHz Interferometric Submetix Swath Bathy Sonar System; SEA Swath Processor,
v. 2.05, SEA Grid Processor v. 2.05, was used for geophysical surveying.
The 2005 survey was navigated with a CodaOctopus, Model F180, Differential Global
Positioning System (DGPS). A KVH Industries Inc. azimuth digital
gyro-compass provided ship headings with 0.5 degree accuracy. Navigation
data were recorded using Yo-Nav version 1.19 (Gann, 1992). The sidescan
fish was towed approximately 30 m above the sea floor. The distance of
the fish behind the ship was not known during this survey and must be
estimated when the data are processed in order to produce the sidescan
image mosaics. The resolution of the processed data mosaics is 0.25 m.
This is one of a collection of digital files of a geographic
information system of spatially referenced data related to
the USGS Coastal and Marine Geology Program Nearshore Benthic Habitat Mapping
Project. See <http://walrus.wr.usgs.gov/research/projects/benthic_hab.html> for more information.


Supplemental_Information:

Additional information about the field activities from
which this data set was derived are available online at <http://walrus.wr.usgs.gov/infobank/k/k105ps/html/k-1-05-ps.meta.html>


Any use of trade, product, or firm names is for descriptive purposes
only and does not imply endorsement by the
U.S. Government.ent.


Although this Federal Geographic Data Committee-compliant metadata
file is intended to document the data set in nonproprietary form,
as well as in ArcInfo format, this metadata file may include some
ArcInfo-specific terminology.




  1. How should this data set be cited

    Sagy, Yael, and Finlayson, David, 2007, all_back.txt - Sidescan sonar backscatter image (for the entier study area) : USGS Data Series 320-XXXX (publication in process), U.S. Geological Survey, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover

    West_Bounding_Coordinate: -123.636376
    East_Bounding_Coordinate: -123.589273
    North_Bounding_Coordinate: 48.162431
    South_Bounding_Coordinate: 48.137074

  3. What does it look like

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

    Beginning_Date: 15-Mar-2005
    Ending_Date: 31-Mar-2005
    Currentness_Reference: Ground Condition

  5. What is the general form of this data set

    Geospatial_Data_Presentation_Form: map

  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 11163 x 13926, type Pixel

    2. What coordinate system is used to represent geographic features

  7. How does the data set describe geographic features

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

    The authors would like to thank, Larry Kooker, Mike Boyle, Gerry Hatcher, Dave Hogg, and Hank Chezar at the USGS Marine Facility (Redwood City, CA) contributed field support and logistical support. Andrew Stevenson from the USGS Coastal and Marine Program. The R/V Karluk was piloted by Katherine Peet from NOAA.

  3. To whom should users address questions about the data

    Guy R. Cochrane
    United States Geological Survey (USGS) Coastal and Marine Geology Program (CMGP)
    Geophysicist
    USGS, MailStop 999, 400 Natural Bridges Ave.
    Santa Cruz, CA 95060
    USA

    (831) 427-4745 (voice)
    (831) 427-4709 (FAX)
    gcochrane@usgs.gov

Why was the data set created


These data are intended for science researchers, students, policy
makers, and the general public. The data can be
used with geographic information systems (GIS) software
to display geologic and oceanographic information.


How was the data set created

  1. From what previous works were the data drawn

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

    Date: 15-Sep-2006 (process 1 of 3)
    The following processing steps were applied in the same manner to all of the five backscatter grids: amp_east1_st, amp_mid_1_st, amp_mid_2_st, amp_west_1_st, am-_west_2_st. Started with .sxr files that were the output from A 234 kHz Interferometric Submetrix
    Sonar System, We used Sonar WiazMap4 to process the sonar data. after importing the .sxr files to Sonar WiazMap4 we used the sonar file manager tool to check and correct the navigation data.Manually bottom-tracked each line.
    Applied signal processing functions by setting the Automatic Gain Control (AGC), Beam Angle Correction (BAC), set Resolution to 35 and Darkness to 50, project sonar data using sensor headings.
    Individually exported each line as a GeoTif file with resolution of 0.25 meter/pixel.

    Date: 25-Sep-2006 (process 2 of 3)
    In ArcMap convert the .TIF files to ESRIGRID using Raster to Other command. Import the lines according to track line number and remov NoData raster cells using the ArcGIS Con statement.

    Date: 09-Sep-2006 (process 3 of 3)
    Mosaiced adjacent backscatter lines. Mosaicing was done by manually drawing a mask around the best possible data for each line and it's overlapping lines. Best possible data was determined subjectively and included the least no data values as possible in the overlapping areas. Merging the masked lines (create a mosaic) together using Mosaic To New Raster with the option "First" such that the better lines are on top.

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

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

  1. How well have the observations been checked

    Accuracy Unknown

  2. How accurate are the geographic locations

    On the order of 10 meters.

  3. How accurate are the heights or depths

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

    Completeness unknown

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

    Logical Consistency untested.

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)

    United States Geological Survey (USGS) Coastal and Marine Geology Program (CMGP)
    c/o Guy R. Cochrane
    Geophysicist
    USGS, 400 Natural Bridges Drive
    Santa Cruz, CA 95060-5792
    USA

    (831) 427-4754 (voice)
    (831) 427-4748 (FAX)
    gcochrane@usgs.gov

  2. What's the catalog number I need to order this data set

  3. What legal disclaimers am I supposed to read


    Please recognize the U.S. Geological Survey (USGS) as the source of
    this information.


    Although these data have been used by the U.S. Geological Survey,
    U.S. Department of the Interior, 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 U.S. Geological Survey in
    the use of this data, software, or related materials.


  4. How can I download or order the data

Who wrote the metadata

Dates:
Last modified: 2007
Last Reviewed: 2007
Metadata author:
United States Geological Survey (USGS) Coastal and Marine Geology Program (CMGP)
c/o Guy R. Cochrane
Geophysicist
USGS, 400 Natural Bridges Drive
Santa Cruz, CA 95060-5792
USA

(831) 427-4754 (voice)
(831) 427-4748 (FAX)
gcochrane@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)

Generated by mp version 2.9.2 on Fri Jul 27 12:09:44 2007