xenial (1) project.1gmt.gz

Provided by: gmt-common_5.2.1+dfsg-3build1_all bug

NAME

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

SYNOPSIS

       project  [  table ] cx/cy [ azimuth ] [ bx/by ] [ flags ] [ dist[/colat][+] ] [ [w][l_min/l_max] ] [  ] [
       ] [  ] [ px/py ] [ [level] ] [ w_min/w_max ] [ -b<binary> ] [ -d<nodata> ] [ -f<flags> ] [ -g<gaps>  ]  [
       -h<headers> ] [ -i<flags> ] [ -s<flags> ] [ -:[i|o] ]

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

DESCRIPTION

       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 = -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.

       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.

REQUIRED ARGUMENTS

       -Ccx/cy
              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 pole.

OPTIONAL ARGUMENTS

       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.

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

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

       -Fflags
              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.

       -Gdist[/colat]
              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 + the we will report the position of the pole as part of the segment header
              [no header].

       -L[w][l_min/l_max]
              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.

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

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

       -Ww_min/w_max
              Width controls. Project only those points whose q coordinate is within w_min < q < w_max.

       -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.

       -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 (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 use just -).

       -+ 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 options, then exits.

       --version
              Print GMT version and exit.

       --show-datadir
              Print full path to GMT share directory and exit.

ASCII FORMAT PRECISION

       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, whereas other values are formatted according to
       FORMAT_FLOAT_OUT. Be aware that the format in effect can lead to loss of precision in the  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.

EXAMPLES

       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 10km along a small circle of colatitude 60 from 10N,50W to 30N,10W:

              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, run:

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

       then  flow.nc  is  a  file in the same area as pacific_topo.nc, but flow contains the latitudes about the
       pole of the projection. You now can use grdcontour on flow.nc 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.

SEE ALSO

       fitcircle, gmt, gmtvector, mapproject, grdproject

       2015, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe