MB-System Unix Manual Page: mbrollbias

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    mbrollbias
    Section:  MB-System 5.0  (1)
    Updated:  26 October 2009
    Index

    NAME

    mbrollbias - Assess roll bias of swath sonar sonar systems.

    VERSION

    Version 5.0

    SYNOPSIS

    mbrollbias -Fformat1/format2 -Llonflip -Ifile1 -Jfile2 -Rwest/east/south/north [-Dxdim/ydim -H -V]

    DESCRIPTION

    mbrollbias is a utility used to assess roll bias of swath sonar
    sonar systems using bathymetry data from two swaths covering the same
    seafloor in opposite directions. The program takes two input
    files and calculates best fitting planes for each dataset.
    The roll bias is calculated by solving for a common roll bias
    factor which explains the difference between the seafloor
    slopes observed on the two swaths.  This approach assumes that
    pitch bias is not a factor; this assumption is most correct when
    the heading of the two shiptracks are exactly opposite. The area is
    divided into a number of rectangular regions and calculations are done
    in each region containing a sufficient number of data from both
    swaths.  The data contained in the two datafiles should be processed to
    ensure that no artifacts will bias the roll bias calculations.
    Typically, this means using mbclean and or mbedit to
    remove noisy outer beams.
    A positive roll bias value means that the the vertical reference
    used by the swath sonar system is biased to starboard,
    giving rise to shallow bathymetry to port and deep bathymetry
    to starboard.  Results are written to stdout.

    AUTHORSHIP

    David W. Caress (caress@mbari.org)

      Monterey Bay Aquarium Research Institute

    Dale N. Chayes (dale@ldeo.columbia.edu)

      Lamont-Doherty Earth Observatory

    OPTIONS

    -F

    format1/format2

    Sets the MBIO format identifiers for the first and
    second data files, respectively.
    This program uses the MBIO library and will read or write any swath sonar
    format supported by MBIO. A list of the swath sonar data formats
    currently supported by MBIO and their identifier values
    is given in the MBIO manual page.
    -D

    xdim/ydim

    The area specified using the -R option is divided up into
    a grid of rectangular regions; roll bias calculations are done
    in each of these regions providing sufficient data is available
    from both data files.  This option sets the dimensions of the
    region grid.  Use xdim = ydim = 1 to make one
    calculation for the entire area.
    Default:  xdim = ydim = 1.
    -H

    This "help" flag cause the program to print out a description
    of its operation and then exit immediately.
    -I

    file1

    Sets the filename of the first data file to be analyzed.
    -J

    file2

    Sets the filename of the second data file to be analyzed.
    -L

    lonflip

    Sets the range of the longitude values returned.
    If lonflip=-1 then the longitude values will be in
    the range from -360 to 0 degrees. If lonflip=0
    then the longitude values will be in
    the range from -180 to 180 degrees. If lonflip=1
    then the longitude values will be in
    the range from 0 to 360 degrees.
    Default: lonflip = 0.
    -R

    west/east/south/north

    Sets the longitude and latitude bounds of the area of the roll bias test.
    -V

    The -V option causes the program to print out the program name
    and version during execution.

    EXAMPLE

    Suppose you want to calculate roll bias using two coincident swaths
    of Hydrosweep DS data collected in nearly opposite directions.
    Run mbrollbias as follows:

            mbrollbias -R-51.07/-50.98/9.0166/9.117 -D1/1 -F22/22

                    -Ihs_leg1_z.mb22 -Jhs_leg2_z.mb22 -V

    The output looks like:

     Program mbrollbias

     Version $Id: mbrollbias.1 1783 2009-10-26 23:33:35Z caress $

     MB-system Version 4.00

     mbrollbias Parameters:

     Input file 1:     hs_leg1_z.mb22

     Input file 2:     hs_leg2_z.mb22

     Region grid bounds:

       Longitude:  -51.0700  -50.9800

       Latitude:     9.0166    9.1170

     Region grid dimensions: 1 1

     Longitude interval: 0.090000 degrees or 9.894392 km

     Latitude interval:  0.100400 degrees or 11.104426 km

     Longitude flipping:   0

     4840 depth points counted in hs_leg1_z.mb22

     1733 depth points counted in hs_leg2_z.mb22

     4840 depth points read from hs_leg1_z.mb22

     1733 depth points read from hs_leg2_z.mb22

     Region 0 (0 0) bounds:

         Longitude:  -51.0700  -50.9800

         Latitude:     9.0166    9.1170

     First data file:    hs_leg1_z.mb22

         Number of data: 4840

         Mean heading:   107.845062

         Plane fit:      4.759709 -0.002327 -0.004623

     Second data file:   hs_leg2_z.mb22

         Number of data: 1733

         Mean heading:   302.022793

         Plane fit:      4.640304 0.008438 0.008494

     Roll bias:   -0.007288 (-0.417598 degrees)

     Roll bias is positive to port, negative to starboard.

     A postive roll bias means the ship rolls to port,

         giving rise to shallow bathymetry to port and

         deep bathymetry to starboard.

    SEE ALSO

    mbsystem(l)

    BUGS

    Probably.

     Index

    NAME
    VERSION
    SYNOPSIS
    DESCRIPTION
    AUTHORSHIP
    OPTIONS
    EXAMPLE
    SEE ALSO
    BUGS

Last Updated: 26 October 2009

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