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       project  -  project  data  along  a  line  or  great  circle, generate a profile track, or
       translate coordinates.


       project [ infile ] -Fflags -Ccx/cy [ -Aazimuth ] [ -Dd|g ]  [  -Ebx/by  ]  [  -Gdist  ]  [
       -H[nrec]  ]  [ -L[w][l_min/l_max] ] [ -M[flag] ] [ -N ] [ -Q ] [ -S ] [ -Tpx/py ] [ -V ] [
       -Ww_min/w_max ] [ -: ] [ -bi[s][n] ] [ -bo[s][n] ]


       project reads arbitrary (x, y[, z]) data from standard input [or infile ]  and  writes  to
       standard output any combination of (x, y, z, p, q, r, s), where (p, q) are the coordinates
       in the projection, (r, s) is the position in the (x, y) coordinate system of the point  on
       the  profile  (q  = 0 path) closest to (x, y), and z is all remaining columns in the input
       (beyond the required x and y columns).  Alternatively, project may be used to generate (r,
       s,  p)  triples  at  equal  increments dist along a profile. In this case ( -G option), no
       input is read.  Projections are defined in any (but only) one of three  ways:  (Definition
       1)  By a Center -C and an Azimuth -A in degrees clockwise from North.  (Definition 2) By a
       Center -C and end point E of the projection path -E.  (Definition 3) By a Center -C and  a
       roTation  pole  position  -T.   To  spherically project data along a great circle path, an
       oblique coordinate system is created which has its equator along that path, and  the  zero
       meridian  through  the  Center. Then the oblique longitude (p) corresponds to the distance
       from the Center along the great circle, and the oblique latitude (q)  corresponds  to  the
       distance  perpendicular  to  the  great  circle  path.  When  moving in the increasing (p)
       direction, (toward B or in the azimuth direction), the positive (q) direction is  to  your
       left.   If  a Pole has been specified, then the positive (q) direction is toward the pole.
       To specify an oblique projection, use the -T option to set the Pole. Then the  equator  of
       the  projection  is  already  determined  and  the  -C  option is used to locate the p = 0
       meridian. The Center cx/cy will be taken as a point through  which  the  p  =  0  meridian
       passes.  If you do not care to choose a particular point, use the South pole (ox = 0, oy =
       -90).  Data can be selectively windowed by using the -L and -W options. If -W is used, the
       projection  Width is set to use only points with w_min < q < w_max. If -L is set, then the
       Length is set to use only those points with l_min < p < l_max. If the -E option  has  been
       used  to  define  the  projection,  then  -Lw  may be selected to window the length of the
       projection  to  exactly  the  span  from  O  to  B.   Flat  earth  (cartesian)  coordinate
       transformations can also be made. Set -N and remember that azimuth is clockwise from North
       (the y axis), NOT the usual cartesian theta, which is counterclockwise from  the  x  axis.
       azimuth  =  90 - theta.  No assumptions are made regarding the units for x, y, r, s, p, q,
       dist, l_min, l_max, w_min, w_max.  If -Q is selected, map units are assumed and x, y, r, s
       must  be  in degrees and p, q, dist, l_min, l_max, w_min, w_max will be in km.  project is
       CASE SENSITIVE. Use UPPER  CASE  for  all  one-letter  designators  which  begin  optional
       arguments. Use lower case for the xyzpqrs letters in -flags.

       -C     cx/cy  sets  the origin of the projection, in Definition 1 or 2. If Definition 3 is
              used (-T), then cx/cy are the coordinates of a point through which the oblique zero
              meridian (p = 0) should pass.


       infile name of ASCII (or binary, see -bi) file(s) with 2 or more columns holding (x,y,[z])
              data values.  If no filenames are given, project will read from standard input.  If
              the -G option is selected, no input data are read.

       -F     Specify  your desired output using any combination of xyzpqrs, in any order. Do not
              space between the letters. Use lower case. The output will  be  ASCII  (or  binary)
              columns  of  values  corresponding  to  xyzpqrs. If both input and output are using
              ASCII format then the z data are treated as textstring(s).  If  the  -G  option  is
              selected, the output will be rsp.

       -A     azimuth defines the azimuth of the projection (Definition 1).

       -D     Set  the  location of the Discontinuity in longitude (r coordinate). -Dd will place
              the discontinuity at the Dateline,  (-180  <  r  <  180);  -Dg  will  place  it  at
              Greenwich, (0 < r < 360).  Default usually falls at dateline due to atan2 calls.

       -E     bx/by defines the end point of the projection path (Definition 2).

       -G     dist  Generate  mode.  No  input is read. Create (r, s, p) output points every dist
              units of p. See -Q option.

       -H     Input file(s) has Header record(s). Number of header  records  can  be  changed  by
              editing your .gmtdefaults file. If used, GMT default is 1 header record.

       -L     Length controls. Project only those points whose p coordinate is within l_min < p <
              l_max.  If -E has been set, then you may use -Lw to stay within the distance from C
              to E.

       -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.

       -N     Flat  earth. Make a cartesian coordinate transformation in the plane. [Default uses
              spherical trigonometry.]

       -Q     Map type units, i.e., project assumes x, y, r, s are in degrees while p,  q,  dist,
              l_min,  l_max, w_min, w_max are in km. If -Q is not set, then all these are assumed
              in same units.

       -S     Sort the output into increasing p order. Useful when projecting random data into  a
              sequential profile.

       -T     px/py sets the position of the roTation pole of the projection. (Definition 3).

       -V     Selects  verbose  mode,  which  will  send progress reports to stderr [Default runs

       -W     Width controls. Project only those points whose q coordinate is within w_min < q  <

       -:     Toggles   between   (longitude,latitude)   and  (latitude,longitude)  input/output.
              [Default is (longitude,latitude)].  Applies to geographic coordinates only.

       -bi    Selects binary input. Append s for single precision [Default is double].  Append  n
              for the number of columns in the binary file(s).  [Default is 2 input columns].

       -bo    Selects binary output. Append s for single precision [Default is double].


       To generate points every 10km along a great circle from 10N,50W to 30N,10W, try:

       project -C-50/10 -E-10/30 -G10 -Q > great_circle_points.xyp

       (Note that great_circle_points.xyp could now be used as input for grdtrack, etc. ).

       To  project  the shiptrack gravity, magnetics, and bathymetry in c2610.xygmb along a great
       circle through an origin at 30S, 30W, the great circle having an azimuth of  N20W  at  the
       origin,  keeping only the data from NE of the profile and within +/- 500 km of the origin,

       project c2610.xygmb -C-30/-30 -A-20 -W-10000/0 -L-500/500 -Fpz -Q > c2610_projected.pgmb

       (Note in this example that -W-10000/0 is used to admit any value with a large  negative  q
       coordinate.  This will take those points which are on our right as we walk along the great
       circle path, or to the NE in this example.)

       To make a cartesian coordinate transformation of mydata.xy so that the new  origin  is  at
       5,3 and the new x axis (p) makes an angle of 20 degrees with the old x axis, try:

       project mydata.xy -C5/3 -A70 -Fpq > mydata.pq

       To  take data in the file pacific.lonlat and transform it into oblique coordinates using a
       pole from the hotspot reference frame and placing the oblique zero meridian (p =  0  line)
       through Tahiti, try:

       project pacific.lonlat -T-75/68 -C-149:26/-17:37 -Fpq > pacific.pq

       Suppose  that  pacific_topo.grd is a grdfile of bathymetry, and you want to make a file of
       flowlines in the hotspot reference frame. If you try:

       grd2xyz pacific_topo.grd | project -T-75/68 -C0/-90 -Fxyq | xyz2grd -Retc -Ietc -Cflow.grd

       then flow.grd is a file in the same  area  as  pacific_topo.grd,  but  flow  contains  the
       latitudes  about  the  pole  of the projection.  You now can use grdcontour on flow.grd to
       draw lines of constant oblique latitude, which are flow lines in the hotspot frame.

       If you have an arbitrarily rotation pole px/py and you would like to draw an oblique small
       circle  on  a map, you will first need to make a file with the oblique coordinates for the
       small circle (i.e., lon = 0-360, lat is constant), then create a file  with  two  records:
       the  north  pole  (0/90) and the origin (0/0), and find what their oblique coordinates are
       using your rotation pole. Now, use the projected North pole and origin coordinates as  the
       rotation  pole  and  center, respectively, and project your file as in the pacific example
       above. This gives coordinates for an oblique small circle.


       fitcircle(1gmt), gmt(1gmt), mapproject(1gmt), grdproject(1gmt)

                                            1 Jan 2004                                 PROJECT(l)