MB-System Unix Manual Page
mbvoxelclean
Section: MB-System 5.0 (1)
Updated: 9 October 2018
Index
NAME
mbvoxelclean - 3D density filter.used to flag and unflag swath soundings,
particularly from lidar sensors.
VERSION
Version 5.0
SYNOPSIS
- mbvoxelclean
-
[
--verbose
--help
--input=infile
--input=datalist
--format=value
--voxel-size=xysize[/zsize]
--occupy-threshold=value
--count-flagged
--flag-empty
--ignore-empty
--unflag-occupied
--ignore-occupied
--range-minimum=value
--range-maximum=value
]
DESCRIPTION
mbvoxelclean identifies and flags artifacts in swath bathymetry data
using a 3D density filter. The notion applied is that true targets
(e.g. the seafloor) result in dense regions of soundings while sparse soundings
in the water column or the subsurface are erroneous and can be flagged as bad.
This technique is more appropriate for lidar data than multibeam sonar data.
The resulting sounding edit events are output to edit save files which can be
applied to the data by the program mbprocess. These are the same edit save
files created and/or modified by mbedit, mbeditviz, mbedit,
and mbclean. The input data are one swath file or a datalist referencing
multiple swath files. Each file is read and processed separately.
The rectangular prism including all of the flagged and unflagged soundings
is divided into 3D voxels of the specified size. All of the soundings are
read into memory and associated with one of the voxels. Once all of
data are read, a density filter is applied such that containing more than a
specified threshold of soundings are considered to be occupied by a valid target and
voxels containing less than the threshold are considered to be empty.
The user may specify one or both of the following actions:
1) Previously unflagged soundings in an empty voxel are flagged as bad.
2) Previously flagged soundings in a full voxel are unflagged.
This program will also apply specified minimum and maximum range filters.
If a sounding's flag status is changed, that flagging action is output
to the edit save file of the swath file containing that sounding. This
program will create edit save files if necessary, or append to those that
already exist.
MB-SYSTEM AUTHORSHIP
David W. Caress
Monterey Bay Aquarium Research Institute
Dale N. Chayes
Center for Coastal and Ocean Mapping
University of New Hampshire
Christian do Santos Ferreira
MARUM - Center for Marine Environmental Sciences
University of Bremen
OPTIONS
- --verbose
-
Normally, mbvoxelclean works "silently" without outputting anything to the stderr
stream. If verbosity is specified, then mbvoxelclean works in a "verbose" mode and
outputs information about the files processed and the numbers of soundings flagged
and unflagged.
- --help
-
This "help" flag cause the program to print out a description of its operation and then exit immediately.
- --input=infile
-
- --input=datalist
-
Sets the input filename. If format > 0 (set with the --format option) then the
swath sonar data contained in infile is read and processed. If format < 0,
then infile is assumed to be a datalist, which is an ascii file containing a list of the input
swath sonar data files to be processed and their formats. The program will
read and process the data in each one of these files. In
the infile file, each data file should be followed by a data format identifier, e.g.:
datafile1 11
datafile2 24
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: datalist = "datalist.mb-1".
- --format=value
-
Sets the data format id of the input file specified with the --input option.
If format < 0, then the input file specified
with the -I option will actually contain a list of input swath sonar
data files. 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.
- --voxel-size=xysize[/zsize]
-
Sets the size of the voxels used for calculating the density filter, in meters.
Each voxel has uniform east-west (x) and north-south (y) width specified by
xysize. The vertical (z) voxel width zsizecan be different, but
matches xysize if not specified.
- --occupy-threshold=value
-
Sets the count threshold used to determine if a voxel is occupied or empty. If
the number of counted soundings within a voxel is >= threshold, then that
voxel is occupied. Otherwise the voxel is empty.
- --count-flagged
-
If this option is specified then the soundings counted to determine if voxels
are occupied or empty includes all soundings, including those previously flagged
as bad. Otherwise only soundings that are unflagged before mbvoxelclean
is run are counted.
- --flag-empty
-
If this option is specified then any unflagged soundings in voxels considered
empty are flagged as bad. This is the default behavior.
- --ignore-empty
-
If this option is specified then any unflagged soundings in voxels considered
empty are are left unflagged.
- --unflag-occupied
-
If this option is specified then any flagged soundings in voxels considered
occupied are unflagged. This is the default behavior.
- --ignore-occupied
-
If this option is specified then any flagged soundings in voxels considered
occupied are left flagged. This is the default behavior.
- --range-minimum=min-range
-
If a min-range value is specified, then any unflagged soundings that are
closer to the sensor than min-range are flagged.
- --range-maximum=max-range]";
-
If a max-range value is specified, then any unflagged soundings that are
farther from the sensor than max-range are flagged.
EXAMPLES
Suppose one wishes to filter the soundings in three lidar files in the format
produced by the 3D at Depth WiSSL sensor (WiSSL = Wide Swath Subsea Lidar).
A datalist referencing these six files exists as the file datalist.mb-1 and
has the contents:
20180925_145000_NorthernSteep.mb233 233
20180925_145100_NorthernSteep.mb233 233
20180925_145200_NorthernSteep.mb233 233
Use the following to apply a density filter to each of these files using voxels
that are 0.04 m X 0.04 m X 0.04 m and an occupy threshold of 5. This command
causes mbvoxelclean to flag any soundings found in voxels containing less
than 5 valid soundings.
mbvoxelclean --input=datalist.mb-1 \
--voxel-size=0.04/0.04 \
--occupy-threshold=5 \
--flag-empty \
--verbose
The verbose output looks like:
Program mbvoxelclean
Version $Id: $
MB-system Version 5.6.002
---------------------------------
Processing 20180925_145000_NorthernSteep.mb233...
Actually reading 20180925_145000_NorthernSteep.mb233.fbt...
Opening edit save file...
5454 survey data records processed
4362859 beams good originally
25495 beams flagged originally
8701246 beams null originally
2615 beams flagged by density filter
0 beams unflagged by density filter
0 beams flagged by minimum range filter
0 beams unflagged by maximum range filter
---------------------------------
Processing 20180925_145100_NorthernSteep.mb233...
Actually reading 20180925_145100_NorthernSteep.mb233.fbt...
Opening edit save file...
5452 survey data records processed
4361125 beams good originally
24250 beams flagged originally
8699425 beams null originally
3051 beams flagged by density filter
0 beams unflagged by density filter
0 beams flagged by minimum range filter
0 beams unflagged by maximum range filter
---------------------------------
Processing 20180925_145200_NorthernSteep.mb233...
Actually reading 20180925_145200_NorthernSteep.mb233.fbt...
Opening edit save file...
5453 survey data records processed
4361528 beams good originally
30589 beams flagged originally
8695083 beams null originally
17709 beams flagged by density filter
0 beams unflagged by density filter
0 beams flagged by minimum range filter
0 beams unflagged by maximum range filter
---------------------------------
MBvoxelclean Processing Totals:
---------------------------------
3 total swath data files processed
16359 total survey data records processed
13085512 total beams good originally
80334 total beams flagged originally
26095754 total beams null originally
0 total beams flagged in old esf file
0 total beams unflagged in old esf file
23375 total beams flagged by density filter
0 total beams unflagged by density filter
0 total beams flagged by minimum range filter
0 total beams unflagged by maximum range filter
SEE ALSO
mbsystem(1), mbedit(1),
mbinfo(1) mbprocess(1),
BUGS
Hay errores aqui.
Index
- NAME
-
- VERSION
-
- SYNOPSIS
-
- DESCRIPTION
-
- MB-SYSTEM AUTHORSHIP
-
- OPTIONS
-
- EXAMPLES
-
- SEE ALSO
-
- BUGS
-
Last Updated: 9 October 2018