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chanwest_back.txt - Sidescan sonar backscatter image for Channel West in the Nearshore Benthic Habitat Mapping Project S. California map series.

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Frequently-anticipated questions:

What does this data set describe?

Title:
chanwest_back.txt - Sidescan sonar backscatter image for Channel Westin the Nearshore Benthic Habitat Mapping Project S. California map series.
Abstract:
The sidescan sonar image of the nearshore seafloor (0 to 100 m water depths)of the Santa Barbara Channel area was mosaicked from data collectedin 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 GlobalPositioning System (DGPS). A KVH Industries Inc. azimuth digitalgyro-compass provided ship headings with 0.5 degree accuracy. Navigationdata were recorded using Yo-Nav version 1.19 (Gann, 1992). The sidescanfish was towed approximately 30 m above the seafloor. The distance ofthe fish behind the ship was not known during this survey and must beestimated when the data are processed in order to produce the sidescanimage mosaics. The resolution of the processed data mosaics is 0.2 m.The data are presented here at a resolution of 1 m.This is one of a collection of digital files of a geographicinformation system of spatially referenced data related tothe USGS Coastal and Marine Geology Program Nearshore Benthic Habitat MappingProject. See <http://walrus.wr.usgs.gov/nearshorehab> for more information.

Supplemental_Information:
Any use of trade, product, or firm names is for descriptive purposesonly and does not imply endorsement by theU.S. Government.

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

  1. How should this data set be cited?

    Golden, Nadine E. , and Cochrane, Guy R. , 2007, chanwest_back.txt - Sidescan sonar backscatter image for Channel West in the Nearshore Benthic Habitat Mapping Project S. California map series.: Open-File Report 2007-1271, U.S. Geological Survey, Santa Cruz, CA.

    Online Links:

    This is part of the following larger work.

    Cochrane, Guy R. , Golden, Nadine, Dartnell, Pete, Schroeder, Donna, Conrad, Jamie, and Stevenson, Andy, 2007, Seafloor Mapping and Benthic Habitat GIS for Southern California, Volume III.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -119.643628
    East_Bounding_Coordinate: -119.471725
    North_Bounding_Coordinate: 34.390598
    South_Bounding_Coordinate: 34.320467

  3. What does it look like?

    images/chanwest_back.jpg (JPEG)
    Image showing coverage ofChannel West backscatter data ArcInfo format.

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

    Beginning_Date: 08-Aug-2005
    Ending_Date: 27-Aug-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 7308 x 7325, 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?

  3. To whom should users address questions about the data?

    Guy R. Cochrane
    U.S. Geological Survey, Coastal and Marine Geology
    Geophysicist
    USGS Pacific Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA 95060-5792
    USA

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

Why was the data set created?

These data are intended for science researchers, students, policymakers, and the general public. The data can beused with geographic information systems (GIS) softwareto 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: 02-Jul-2006 (process 1 of 5)
    Started with SXP files that were the output from A 468 kHz Interferometric SubmetixSwath Bathy Sonar System. Based on the Julian date at original data collection,individually imported each raw backscatter file into ìSEA Swath Processor Real-Time Software System.îConfigured the way the data was processed in ìSEA Swath Processorî by inputting adjustment and offset information, such as ship's motion, tides, velocity of sound, and relative sensor positions.

    Date: 08-Feb-20055 (process 2 of 5)
    Used the ìSonarWiz.MAP Sonar File Managerî tool: check and correct the navigation data.Manually ìbottom-trackedî each line.Applied signal processing functions by setting the Automatic Gain Control (AGC), Beam Angle Correction (BAC),project sonar data using sensor headings.Individually exported the line as a GeoTif file.

    Date: 08-Feb-20055 (process 3 of 5)
    Looped through the directory of GeoTif files and convert GeoTif to ArcGIS raster format.Removed ìNoDataî raster cells using the ArcGIS Con statement; and projected the data to WGS 1984 UTM Zone 11.
      **** Ascii to ArcRaster & Project Pyramids (Python Script)****  # ---------------------------------------------------------------------------  # ascii_to_arcraster_project_pyramids_stand_alone.py          # Created on: Tuesday Oct 04 2006  # Nadine Golden  # ---------------------------------------------------------------------------  # Import system modules  import glob, sys, string, os, win32com.client  # Create the Geoprocessor object  gp = win32com.client.Dispatch("esriGeoprocessing.GpDispatch.1")  # Load required toolboxes...  gp.AddToolbox("E:/ArcGIS/ArcToolbox/Toolboxes/Data Management Tools.tbx")  gp.AddToolbox("E:/ArcGIS/ArcToolbox/Toolboxes/Conversion Tools.tbx")  files = glob.glob("F:/test/grids/*asc")  for file in files:      (basename, ext) = os.path.splitext(file)      ingrid = file      outgrid = basename + "tmp"      os.system("scii_to_arcraster_project_pyramids_stand_alone.py %s %s" % (ingrid, outgrid))      # Process: ASCII to Raster...      gp.ASCIIToRaster_conversion(ingrid, outgrid, "INTEGER")  ##    # Process: Define Projection...  ##    gp.DefineProjection_management(outgrid,                                                                     "PROJCS['NAD_1983_UTM_Zone_11N',GEOGCS['GCS_North_American_1983',DATUM['D_North_American_1983',            SPHEROID['GRS_1980',6378137.0,298.257222101]],            PRIMEM['Greenwich',0.0],            UNIT['Degree',0.0174532925199433]],            PROJECTION['Transverse_Mercator'],            PARAMETER['False_Easting',500000.0],            PARAMETER['False_Northing',0.0],            PARAMETER['Central_Meridian',-117.0],            PARAMETER['Scale_Factor',0.9996],            PARAMETER['Latitude_Of_Origin',0.0],            UNIT['Meter',1.0]]")      # Process: Project Raster...      finalgrid = basename      gp.ProjectRaster_management(outgrid, finalgrid,                 "PROJCS['WGS_1984_UTM_Zone_11N',GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',          SPHEROID['WGS_1984',6378137.0,298.257223563]],          PRIMEM['Greenwich',0.0],          UNIT['Degree',0.0174532925199433]],          PROJECTION['Transverse_Mercator'],          PARAMETER['False_Easting',500000.0],          PARAMETER['False_Northing',0.0],          PARAMETER['Central_Meridian',-117.0],          PARAMETER['Scale_Factor',0.9996],          PARAMETER['Latitude_Of_Origin',0.0],          UNIT['Meter',1.0]];          -10000 -10000 100000;0 100000;0 100000", "NEAREST", "1")      # Process: Build Pyramids...      gp.BuildPyramids_management(finalgrid)      # Clean up the mess      gp.Delete(outgrid)

    Date: 09-Feb-20055 (process 4 of 5)
    Looped through the directory arcgrids and normalized the backscatter values using the Python script "RasterStats.py."
      **** Rasters Statistics for Normalizing Data (Python Script)****  # ---------------------------------------------------------------------------  # RasterStats.py  # To Calculate the mean value of a raster  # Created on: Thursday Oct 20, 2006  # Nadine Golden  # ---------------------------------------------------------------------------  # Import system modules  import sys, string, os, win32com.client  # Create the Geoprocessor object  gp = win32com.client.Dispatch("esriGeoprocessing.GpDispatch.1")  # Check out any necessary licenses  gp.CheckOutExtension("spatial")  # Load required toolboxes...  gp.AddToolbox("E:/ArcGIS/ArcToolbox/Toolboxes/Spatial Analyst Tools.tbx")  gp.AddToolbox("E:/ArcGIS/RasterStatsTool/RasterStatistics.tbx")  #Directory of grids  gp.Workspace = "F:\\test"  rasterlist = gp.ListRasters()  name = rasterlist.Next()  while name:      print name      # Process: RasterBand Statistics...      mean = gp.RasterBandStatistics(name, "MEAN")      print mean      # Process: Minus...      (indir,basename) = os.path.split(name)      outgrid = os.path.join("F:\\test\\Normalized", basename)      gp.Minus_sa(name, mean, outgrid)      print outgrid      name = rasterlist.Next()

    Date: 22-Jul-2006 (process 5 of 5)
    In ArcGIS, imported lines according to track line number and mosaiced adjacent backscatter lines.Mosaicing was done by manually drawing a mask around the best possible data for each line andit's overlapping lines. Best possible data was determined subjectively and included the leastno data values as possible in the overlapping areas.

  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?

  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?

    Please see the Methods section of <http://pubs.usgs.gov/of/2007/1271/> forinformation about omissions, selection criteria, generalization,definitions used, and other rules used to derive the data set.

  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:
Public domain data from the U.S. government is freely redistributablewith 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 1)

    U.S. Geological Survey, Coastal and Marine Geology
    c/o Guy R. Cochrane
    Geophysicist
    USGS Pacific Science Center, 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?

    Although this data set has been used by the USGS,no warranty, expressed or implied, is made by the USGSas to the accuracy of the data and/or related materials.The act of distribution shall not constitute any such warranty,and no responsibility is assumed by the USGSin the use of these data or related materials.

    Any use of trade, product, or firm names isfor descriptive purposes only and does not implyendorsement by the U.S. Government.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 11-Jul-2007
Metadata author:
U.S. Geological Survey, Coastal and Marine Geology
c/o Nadine Golden
Geographer
USGS Pacific Science Center, 400 Natural Bridges Drive
Santa Cruz, CA 95060-5792
USA

(831) 427-4730 (voice)
(831) 427-4748 (FAX)
ngolden@usgs.gov

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

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