backtracker - Forward and Backward flowlines and hotspot tracks
backtracker [infile(s)] -Estage_file [ -A[young/old] ] [ -C ] [ -Df|b ]
[ -H[nrec] ] [ -Lf|bstep ] [ -M[flag] ] [ -Nupper_age ] [ -Qfixed_age ]
[ -Sfilestem ] [ -Tzero_age ] [ -V ] [ -W[a|t] ] [ -: ] [ -bi[s][n] ] [
backtracker reads (longitude, latitude, age) positions from infiles [or
standard input] and computes projected (x,y,t) coordinates using the
specified rotation parameters. It can either calculate final positions
[Default] or create a sampled track between the initial and final posi-
tions. The former mode allows additional data fields after the first 3
columns which must have (longitude,latitude,age). See option -: on how
to read (latitude,longitude,age) files.
No space between the option flag and the associated arguments.
Use upper case for the option flags and lower case for modifiers.
Data file(s) to be projected. If not given, standard input is
-E Give file with rotation poles and opening angles. This file must
contain one record for each rotation; each record must be of the
lon lat tstart [tstop] ccw-angle [k a b c d e f g]
where tstart [and tstop] are in Ma, with lon, lat, and angle in
degrees. For stage rotations, the oldest stage must be listed
first, whereas for total reconstruction rotations the youngest
rotation is listed first. tstart (tstop) is the age of the old
(young) end of the stage. A covariance matrix, if present, may
be given in the given format. Blank lines and records whose
first column contains # will be ignored.
-A Used in conjunction with -Lb|f to limit the track output to
those sections whose predicted ages fit between the young and
old limits. If -LB|F is used instead then the limits apply to
the stage ids. If no limits are supplied then individual limits
for each seamount are expected in columns 4 and 5 of the input
-C Expect Total Reconstruction Poles (Finite Poles) rather than
Backward Stage Poles [Default]. File format is similar to the
stage pole format except the youngest rotation must be listed
first and that the tstart column is optional (assumed to be 0
-D Set the direction to go: -Df will go forward in time (from
younger to older positions), while -Db will go backward in time
(from older to younger positions) [Default].
used, the third output column will contain the stage id (1 is
youngest) [Default is along-track ages].
-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 Set the maximum age to extend the oldest stage back in time
[Default is no extension].
-Q Assign a fixed age to all positions. Only lon, lat input is
-S When -L is set, the tracks are normally written to stdout as a
multisegment file. Specify a filestem to have each track written
to filestem.#, where # is the track number. The track number is
also copied to the 4th output column.
-T Set the current time [Default is 0 Ma].
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-W Rotates the given input (lon,lat,t) and calculates the confi-
dence ellipse for the projected point. The input point must have
a time coordinate that matches a particular finite rotation
time, otherwise the point will be skipped. Append t or a to out-
put time or angle, respectively, after the projected lon, lat.
After these 2-3 items, we write azimuth, major, minor (in km)
for the 95% confidence ellipse.
-: Toggles between (longitude,latitude) and (latitude,longitude)
input and/or output. [Default is (longitude,latitude)]. Append
i to select input only or o to select output only. [Default
-bi Selects binary input. Append s for single precision [Default is
double]. Append n for the number of columns in the binary
[Default is 3 input columns].
-bo Selects binary output. Append s for single precision [Default is
To backtrack the (x,y,t) points in the file seamounts.d to their origin
(presumably the hotspot), using the DC85.d Euler poles, run
backtracker seamounts.d -Db -EDC85.d > newpos.d
To project flowlines forward from the (x,y,t) points stored in several
3-column, binary, double precision files, run
backtracker points.* -Df -EDC85.d -Lf25 -bo -bi3 > lines.b
GMT4.0 1 Oct 2004 BACKTRACKER(GMTMANSECTION)
Man(1) output converted with