Provided by: gmt-common_5.4.5+dfsg-1_all bug


       project  -  Project  table data onto lines or great circles, generate tracks, or translate


       project [ table ]  -Ccx/cy [  -Aazimuth ] [  -Ebx/by ] [  -Fflags ] [   -Gdist[/colat][+h]
       ]  [   -L[w][l_min/l_max]  ]  [   -N  ]  [   -Q  ]  [   -S ] [  -Tpx/py ] [  -V[level] ] [
       -Ww_min/w_max ] [ -bbinary ] [ -dnodata ] [ -eregexp ] [ -fflags ] [ -ggaps ] [  -hheaders
       ] [ -iflags ] [ -sflags ] [ -:[i|o] ]

       Note: No space is allowed between the option flag and the associated arguments.


       project  reads  arbitrary  (x,  y[,z])  data from standard input [or table ] 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 =

       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.

       Calculations of specific great-circle and  geodesic  distances  or  for  back-azimuths  or
       azimuths are better done using mapproject.

       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.


              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.  The cx/cy is not required to be 90 degrees from  the


       table  One  or  more  ASCII (or binary, see -bi[ncols][type]) data table file(s) holding a
              number of data columns. If no tables are given then we read from standard input.

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

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

              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, see
              -bo) columns of values corresponding to xyzpqrs [Default]. 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.

              Generate mode. No input is read. Create (r, s, p) output points every dist units of
              p.  See -Q option. Alternatively, append /colat for a small circle instead [Default
              is a colatitude of 90, i.e., a great circle]. Use -C and -E to  generate  a  circle
              that  goes  through the center and end point. Note, in this case the center and end
              point cannot be farther apart than 2*|colat|. Finally, if you append +h the we will
              report the position of the pole as part of the segment header [no header].

              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.

       -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
              to be in the same units.

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

              px/py sets the position of the rotation pole of the projection.  (Definition 3).

       -V[level] (more ...)
              Select verbosity level [c].

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

       -bi[ncols][t] (more ...)
              Select native binary input. [Default is 2 input columns].

       -bo[ncols][type] (more ...)
              Select native binary output. [Default is given by -F or -G].

       -d[i|o]nodata (more ...)
              Replace input columns that equal nodata with NaN and do the reverse on output.

       -e[~]"pattern" | -e[~]/regexp/[i] (more ...)
              Only accept data records that match the given pattern.

       -f[i|o]colinfo (more ...)
              Specify data types of input and/or output columns.

       -g[a]x|y|d|X|Y|D|[col]z[+|-]gap[u] (more ...)
              Determine data gaps and line breaks.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more ...)
              Skip or produce header record(s).

       -icols[+l][+sscale][+ooffset][,...] (more ...)
              Select input columns and transformations (0 is first column).

       -s[cols][a|r] (more ...)
              Set handling of NaN records.

       -:[i|o] (more ...)
              Swap 1st and 2nd column on input and/or output.

       -^ or just -
              Print a short message about the syntax of the command, then exits (NOTE: on Windows
              just use -).

       -+ or just +
              Print  an  extensive  usage  (help)  message,  including  the  explanation  of  any
              module-specific option (but not the GMT common options), then exits.

       -? or no arguments
              Print a complete usage (help) message, including the explanation  of  all  options,
              then exits.


       The  ASCII  output formats of numerical data are controlled by parameters in your gmt.conf
       file. Longitude and latitude are formatted according to FORMAT_GEO_OUT, absolute  time  is
       under  the control of FORMAT_DATE_OUT and FORMAT_CLOCK_OUT, whereas general floating point
       values are formatted according to FORMAT_FLOAT_OUT. Be aware that the format in effect can
       lead  to loss of precision in ASCII output, which can lead to various problems downstream.
       If you find the output is not written with enough precision, consider switching to  binary
       output (-bo if available) or specify more decimals using the FORMAT_FLOAT_OUT setting.


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

              gmt 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  generate  points  every 1 degree along a great circle from 30N,10W with azimuth 30 and
       covering a full 360, try:

              gmt project -C10W/30N -A30 -G1 -L-180/180 > great_circle.txt

       To generate points every 10km along a small  circle  of  colatitude  60  from  10N,50W  to

              gmt project -C-50/10 -E-10/30 -G10/60 -Q > small_circle_points.xyp

       To  create a partial small circle of colatitude 80 about a pole at 40E,85N, with extent of
       45 degrees to either side of the meridian defined by the great circle from the pole  to  a
       point 15E,15N, try

              gmt project -C15/15 -T40/85 -G1/80 -L-45/45 > some_circle.xyp

       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,

              gmt 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, use:

              gmt 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, run:

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

       Suppose  that is a grid file of bathymetry, and you want to make a file of
       flowlines in the hotspot reference frame. If you run:

              gmt grd2xyz | project -T-75/68 -C0/-90 -Fxyq | xyz2grd -Retc -Ietc

       then is a file in  the  same  area  as,  but  flow  contains  the
       latitudes  about the pole of the projection. You now can use grdcontour on 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, gmt, gmtvector, grdtrack, mapproject, grdproject, grdtrack


       2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe