Provided by: gmt-common_5.4.5+dfsg-2_all bug


       triangulate  -  Do  optimal  (Delaunay) triangulation and gridding of Cartesian table data


       triangulate [ table ] [  -Cslpfile ] [  -Dx|y ] [  -Eempty ] [  -Ggrdfile ] [  -Iincrement
       ]  [  -Jparameters ] [  -M ] [  -N ] [  -Q[n] ] [  -Rregion ] [  -S ] [  -V[level] ] [  -Z
       ] [ -bbinary ] [ -dnodata ] [ -eregexp ] [ -fflags ] [ -hheaders ] [ -iflags ] [  -r  ]  [
       -:[i|o] ]

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


       triangulate  reads  one  or  more  ASCII  [or binary] files (or standard input) containing
       x,y[,z] and performs Delaunay triangulation, i.e.,  it  find  how  the  points  should  be
       connected  to  give the most equilateral triangulation possible. If a map projection (give
       -R and -J) is chosen then it  is  applied  before  the  triangulation  is  calculated.  By
       default,  the  output  is  triplets  of point id numbers that make up each triangle and is
       written to standard output. The id numbers refer to  the  points  position  (line  number,
       starting  at  0  for  the  first  line) in the input file. As an option, you may choose to
       create a multiple segment file that can be piped through psxy to  draw  the  triangulation
       network.  If  -G  -I are set a grid will be calculated based on the surface defined by the
       planar triangles. The actual algorithm used in the triangulations is either that of Watson
       [1982]  [Default] or Shewchuk [1996] (if installed; type triangulate - to see which method
       is selected). This choice is made  during  the  GMT  installation.   Furthermore,  if  the
       Shewchuk  algorithm  is  installed  then  you  can also perform the calculation of Voronoi
       polygons and optionally grid your data via the natural nearest neighbor algorithm.




       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.


              Read a slope grid (in radians) and compute the propagated uncertainty in the
                     bathymetry  using  the CURVE algorithm [Zambo et al, 20xx].  Requires the -G
                     option to specify the output grid.  Note that the slpgrid  sets  the  domain
                     for  the  output  grid  so -R, -I, [-r] are not required.  Cannot be used in
                     conjunction with -D, -F, -M, -N, -Q, -S and -T.

       -Dx|y  Take either the x- or y-derivatives of surface represented  by  the  planar  facets
              (only used when -G is set).

              Set the value assigned to empty nodes when -G is set [NaN].

              Use triangulation to grid the data onto an even grid (specified with -R -I). Append
              the name of the output grid file. The interpolation is performed  in  the  original
              coordinates,  so  if  your  triangles  are  close  to  the poles you are better off
              projecting all data to a local coordinate system before using triangulate (this  is
              true  of  all  gridding  routines)  or  instead select sphtriangulate.  For natural
              nearest neighbor gridding you must add -Qn.

              x_inc [and optionally y_inc] is the  grid  spacing.  Optionally,  append  a  suffix
              modifier. Geographical (degrees) coordinates: Append m to indicate arc minutes or s
              to indicate arc seconds. If one of the units e,  f,  k,  M,  n  or  u  is  appended
              instead,  the  increment  is assumed to be given in meter, foot, km, Mile, nautical
              mile or US survey foot, respectively, and  will  be  converted  to  the  equivalent
              degrees  longitude  at the middle latitude of the region (the conversion depends on
              PROJ_ELLIPSOID). If y_inc is given but set to 0 it will be reset  equal  to  x_inc;
              otherwise  it  will  be  converted  to  degrees latitude. All coordinates: If +e is
              appended then the corresponding max x (east) or y (north) may be slightly  adjusted
              to  fit  exactly  the  given  increment  [by  default the increment may be adjusted
              slightly to fit the given domain]. Finally, instead of giving an increment you  may
              specify  the  number  of  nodes  desired  by  appending  +n to the supplied integer
              argument; the increment is then recalculated from  the  number  of  nodes  and  the
              domain.  The  resulting  increment  value  depends  on  whether you have selected a
              gridline-registered or pixel-registered grid;  see  App-file-formats  for  details.
              Note:  if -Rgrdfile is used then the grid spacing has already been initialized; use
              -I to override the values.

       -Jparameters (more ...)
              Select map projection.

       -M     Output triangulation network as multiple  line  segments  separated  by  a  segment
              header record.

       -N     Used  in  conjunction  with  -G  to  also  write the triplets of the ids of all the
              Delaunay vertices [Default only writes the grid].

       -Q[n]  Output the edges of the Voronoi cells instead [Default is Delaunay triangle edges].
              Requires  -R and is only available if linked with the Shewchuk [1996] library. Note
              that -Z is ignored on output. Optionally, append n for  combining  the  edges  into
              closed Voronoi polygons.

       -Rxmin/xmax/ymin/ymax[+r][+uunit] (more ...)
              Specify the region of interest.

       -S     Output triangles as polygon segments separated by a segment header record. Requires
              Delaunay triangulation.

       -T     Output edges or polygons even if gridding has been  selected  with  the  -G  option
              [Default  will  not  output  the  triangulation  or Voronoi polygons is gridding is

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

       -Z     Controls whether we read (x,y) or (x,y,z) data and if z should be output when -M or
              -S are used [Read (x,y) only].

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

       -bo[ncols][type] (more ...)
              Select  native  binary  output. [Default is same as input].  Node ids are stored as
              double triplets.

       -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.

       -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).

       -r (more ...)
              Set pixel node registration [gridline]. (Only valid with -G).

       -:[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.


       Regardless  of  the  precision of the input data, GMT programs that create grid files will
       internally hold the grids in 4-byte floating point arrays. This is done to conserve memory
       and  furthermore  most  if  not  all  real  data can be stored using 4-byte floating point
       values. Data with  higher  precision  (i.e.,  double  precision  values)  will  lose  that
       precision  once  GMT  operates  on  the  grid  or  writes  out new grids. To limit loss of
       precision when processing data you should always consider normalizing the  data  prior  to


       To  triangulate  the  points  in the file, store the triangle information in a
       binary file, and make a grid for the given area and spacing, use

              gmt triangulate -bo -R0/30/0/30 -I2 > samples.ijk

       To draw the optimal Delaunay  triangulation  network  based  on  the  same  file  using  a
       15-cm-wide Mercator map, use

              gmt triangulate -M -R-100/-90/30/34 -JM15c | gmt psxy \
                  -R-100/-90/30/34 -JM15c -W0.5p -B1 >

       To instead plot the Voronoi cell outlines, try

              gmt triangulate -M -Q -R-100/-90/30/34 -JM15c | \
                  gmt psxy -R-100/-90/30/34 -JM15c -W0.5p -B1 >

       To combine the Voronoi outlines into polygons and paint them according to their ID, try

              gmt triangulate -M -Qn -R-100/-90/30/34 -JM15c | \
                  gmt psxy -R-100/-90/30/34 -JM15c -W0.5p+cf -L -B1 -Ccolors.cpt -L >

       To grid the data using the natural nearest neighbor algorithm, try

              gmt triangulate -Qn -R-100/-90/30/34 -I0.5


       The  uncertainty  propagation  for bathymetric grids requires both horizontal and vertical
       uncertainties and these are weighted given the local slope.  See the references  for  more


       gmt,  greenspline,  nearneighbor,  pscontour, sphdistance, sphinterpolate, sphtriangulate,


       Watson, D. F., 1982, Acord: Automatic contouring of raw data, Comp. & Geosci., 8, 97-101.

       Shewchuk, J. R., 1996, Triangle: Engineering a 2D  Quality  Mesh  Generator  and  Delaunay
       Triangulator,  First  Workshop  on  Applied  Computational  Geometry  (Philadelphia,  PA),
       124-133, ACM, May 1996.

       Shewchuk's Homepage


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