x2sys_cross - Find and compute Cross-Over Errors
x2sys_cross file(s) OR -Lflist [ -Agap ] [ -Cc|f|g ] [ -Ddeffile ] [
-Fflags ] [ -Gd|g ] [ -Il|a|c ] [ -Jparams ] [-Kcombi.lis] [ -M[flag] [
-Nwindow ] [ -O ] [ -Qe|i ] [ -Sl|uspeed ] [ -TTAG ] [ -Wsize ] [ -V ]
[ -2 ] [ -bo[s] ]
x2sys_cross is used to determine all intersections between or within
tracks, and report the time, position, discrepancies in all observ-
ables, the mean values of the observables, heading along each trackseg-
ment, and the distance along track at the cross-over point. The names
of the files are passed on the command line, or as a list of files with
the -L option. If they are identical or only one name is passed, then
x2sys_cross will also look for internal cross-overs. The optional
-A Ignore crossovers on segments of length > gap [no gap checking].
-C Select procedure for along-track distance calculation:
c Cartesian distances [Default].
f Flat earth distances.
g Great circle distances.
-D Give the definition file for this data format [x2sys].
-F Sets which columns to use. Give a comma-separated list of column
names [Default is all columns].
-G Selects geographical coordinates. Append d for discontinuity at
the Dateline (makes longitude go from -180 to + 180) or g for
discontinuity at Greenwhich (makes longitude go from 0 to 360
-I Sets the interpolation mode. Choose among:
l Linear interpolation [Default].
a Akima spline interpolation.
c Cubic spline interpolation.
-J Selects the map projection. Scale is UNIT/degree, 1:xxxxx, or
width in UNIT (upper case modifier). UNIT is cm, inch, or m,
depending on the MEASURE_UNIT setting in .gmtdefaults4, but this
can be overridden on the command line by appending c, i, or m to
the scale/width value. For map height, max dimension, or min
dimension, append h, +, or - to the width, respectively.
-Jmscale (Mercator - Greenwich and Equator as origin)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard paral-
-Jslon0/lat0/[slat/]scale (General Stereographic)
-Jk[f|s]lon0/scale (Eckert IV (f) and VI (s))
-Jrlon0/scale (Winkel Tripel)
-Jvlon0/scale (Van der Grinten)
-Jp[a]scale[/origin] (polar (theta,r) coordinates, optional a
for azimuths and offset theta )
-Jxx-scale[l|ppow][/y-scale[l|ppow]][d] (Linear, log, and power
More details can be found in the psbasemap man pages.
-K Only process the pair-combinations found in the file combi.lis
[Default process all possible combinations among the specified
files]. Suitable option for passing old x_setup output.
-M Multiple segment file(s). Segments are separated by a special
record. For ASCII files the first character must be flag
[Default is ’>’]. For binary files all fields must be NaN and
-bo[s]n must set the number of output columns explicitly.
-N Maximum number of points to use in the interpolation .
-O Output results using the old XOVER format [Default is X2SYS for-
mat]. This option should only be used with *.gmt-formatted
-Q Append e for external crossovers only, and i for internal
crossovers only [Default is all crossovers].
-R xmin, xmax, ymin, and ymax specify the Region of interest. For
geographic regions, these limits correspond to west, east,
south, and north and you may specify them in decimal degrees or
in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left
type and positions must be as indicated (however, input/output
and plotting formats are flexible).
-S Defines window of track speed within which to calculate
-Sl sets lower speed [Default is 0].
-Su sets upper speed [Default is Infinity].
-T Sets the data set TAG which among other things sets the defini-
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-W Sets maximum time gap (in user units) allowed between points on
either side of a crossover [Default is Infinity].
-2 Report the values of each track at the crossover [Default is the
crossover value and the mean value].
-bo Selects binary output. Append s for single precision [Default is
The COEs found are printed out to standard output in ASCII format
(unless -bo is set). When ASCII is chosen, the output format depends on
whether or not old-style XOVER output (-O) has been selected. If so,
then the first record contains the file names and their start year,
whereas subsequent records have the data for each COE encountered. The
fields written out are lat, lon, time along track #1, time along track
#2, x_gravity, x_magnetics, x_bathymetry, average gravity, average mag-
netics, average bathymetry, heading along track #1, and heading along
track #2. If the default format is chosen then the header record starts
with "> ", and the output format for crossovers are first 8 columns
that contain x, y, time along track #1, time along track #2, distance
along track #1, distance along track #2, heading along track #1, and
heading along track #2, and then pairs of (COE, average value) for each
data type. Sign convention: If lega and legb are passed on the command
line, then the COE value is Value (lega) - Value (legb). It is recom-
mended that the Akima spline is used instead of the natural cubic
spline, since it is less sensitive to outliers that tend to introduce
wild oscillations in the interpolation.
To compute all internal crossovers in the gmt-formatted file c2104.gmt,
and output in the old XOVER format, use
x2sys_cross c2104.gmt -O -Dgmt > c2104.d
To find the crossover locations with bathymetry between the two MGD77
files A13232.mgd77 and A99938.mgd77, try
x2sys_cross A13232.mgd77 A99938.mgd77 -Qe -Dmgd77 -Flon,lat,top >
Man(1) output converted with