mbsmooth
Section:  MB-System 5.0  (l)
Updated:  4 January 2001 
Index


 
NAME

mbsmooth - Smooths swath sonar bathymetry data.

 
VERSION

Version 5.0

 
SYNOPSIS

mbsmooth [-Fformat -Gwidth -Iinfile -Llonflip -Nbuffersize -Ooutfile -Wfilterfile -V -H]

 
DESCRIPTION

mbsmooth applies a spatial domain gaussian filter 
to swath sonar bathymetry data in order to smooth out noise 
in the data.  The width of the filter can be varied as a
function of beam number.
The default input and output streams are stdin and stdout.

 
AUTHORSHIP

David W. Caress (caress@mbari.org)




  Monterey Bay Aquarium Research Institute



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




  Lamont-Doherty Earth Observatory

 
ACKNOWLEDGEMENT

This program is inspired to a large extent by the mb-system
version 1 program mbsmooth by Alberto Malinverno (formerly 
at L-DEO, now at Schlumberger).  The smoothing mechanism
employed in the current version is significantly different
than the nearest-neighbor scheme used in Alberto's program,
so Alberto should not be held responsible for any shortcomings
in the current version.

 
OPTIONS


-F


format



Sets the format for the input and output swath sonar data using 
MBIO integer format identifiers. 
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.
Default: format = 11.
-G


width



Sets the width in meters of the default Gaussian filter.
This value is used for all beams if a filter widths file
is not specified with the -W option.
Default: format = 250.
-H


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


infile



Data file from which the input data will be read. If
no input file is specified, the input will be read
from stdin. Default: infile = stdin.
-L


lonflip



Sets the range of the longitude values used.
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.
-N


buffersize



Sets the maximum number of data records which can be
read into the buffer. In general, data records may be
of several different types (e.g. parameter, position, 
comment) in addition to survey data records. Many data 
formats include many more position data records than
survey data records. Thus, a large buffer may be required
to access a reasonable number of survey data records. 
However, on memory limited machines large buffer sizes
can lead to poor performance due to memory swapping. 
The default value of buffersize = 500 is appropriate 
for most cases, but users can set the buffer size as required.
The absolute maximum buffer size is 5000. 
Default: buffersize = 500.
-O


outfile



Data file to which the output data will be written. If
no output file is specified, the output will be written to
stdout. Default: outfile = stdout.
-W


filterfile



Data file from which filter widths as a function of beam number
are read.  The filter widths should be in the form



       beam  width




where the width is in meters and corresponds the the "w"
value in the Gaussian filter:



       f(r) = exp(-r**2/(w/2)**2) 




Thus, "w" is the full width of the Gaussian filter.
Use of this operation overrides the use of the default filter
width set with the -G option.
-V


Normally, mbsmooth works "silently" without outputting
anything to the stderr stream.  If the
-V flag is given, then mbsmooth works in a "verbose" mode and
outputs the program version being used and all error status messages.


 
EXAMPLES

Suppose one wishes to smooth a noisy Hydrosweep file in
L-DGO binary format (format 24) using a Gaussian spatial domain
filter with a width of 250 meters for all of the beams. 


        mbsmooth -F24 -Ihsnoisy -Ohssmooth -G250


 
SEE ALSO

mbsystem(l)

 
BUGS

It would be good to include other smoothing schemes as options
in this program.  In particular, we should re-implement 
Alberto Malinverno's nearest neighbor averaging algorithm as
well as a median filter algorithm.



 
Index

NAME

VERSION

SYNOPSIS

DESCRIPTION

AUTHORSHIP

ACKNOWLEDGEMENT

OPTIONS

EXAMPLES

SEE ALSO

BUGS

Return to list of MB-System manual pages...

Back to MB-System Home Page...