PSCONTOUR(1)

NAME
pscontour - Contour xyz-data by direct triangulation

SYNOPSIS
pscontour xyzfile -Ccptfile -Jparameters -Rwest/east/south/north[r] [ -A[-][labelinfo] ] [ -Btickinfo ] [ -D[dumpfile] ] [ -Eview_az/view_el ] [ -G[d|f|n|l|L|x|X]info ] [ -H[nrec] ] [ -I ] [ -K ] [ -Lpen ] [ -M[flag] ] [ -N ] [ -O ] [ -P ] [ -S ] [ -Tindexfile ] [ -U[/dx/dy/][label] ] [ -V ] [ -W[+]pen ] [ -Xx-shift ] [ -Yy-shift ] [ -ccopies ] [ -: ] [ -bi[s][n] ] [ -bo[s][n] ]

DESCRIPTION
pscontour reads an ASCII [or binary] xyz-file and produces a raw contour plot by triangulation. By default, the optimal Delaunay triangulation is performed (using either Shewchuk's [1996] or Watson's [1982] method as selected during GMT installation), but the user may optionally provide a second file with network information, such as a triangular mesh used for finite element modeling. In addition to contours, the area between contours may be painted according to the color palette file.

xyzfile
    Raw ASCII (or binary, see -b) xyz data to be contoured.

-C  name of the color palette file. Must have discrete colors if you want to paint the surface (-I). Only contours that have annotation flags set will be annotated.

-J  Selects the map projection. Scale is UNIT/degree, 1:xxxxx, or width in UNIT (upper case modifier). UNIT is cm, inch, or m, depending on the MEASURE_UNIT setting in .gmtdefaults4, but this can be overridden on the command line by appending c, i, or m to the scale/width value. For map height, max dimension, or min dimension, append h, +, or - to the width, respectively.

    CYLINDRICAL PROJECTIONS:

    -Jclon0/lat0/scale (Cassini)
    -Jjlon0/scale (Miller)
    -Jmscale (Mercator - Greenwich and Equator as origin)
    -Jmlon0/lat0/scale (Mercator - Give meridian and standard parallel)
    -Joalon0/lat0/azimuth/scale (Oblique Mercator - point and azimuth)
    -Joblon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
    -Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and pole)
    -Jqlon0/scale (Equidistant Cylindrical Projection (Plate Carree))
    -Jtlon0/scale (TM - Transverse Mercator, with Equator as y = 0)
    -Jtlon0/lat0/scale (TM - Transverse Mercator, set origin)
    -Juzone/scale (UTM - Universal Transverse Mercator)
    -Jylon0/lats/scale (Basic Cylindrical Projection)

    AZIMUTHAL PROJECTIONS:

    -Jalon0/lat0/scale (Lambert).
    -Jelon0/lat0/scale (Equidistant).
    -Jflon0/lat0/horizon/scale (Gnomonic).
    -Jglon0/lat0/scale (Orthographic).
    -Jslon0/lat0/[slat/]scale (General Stereographic)

    CONIC PROJECTIONS:

    -Jblon0/lat0/lat1/lat2/scale (Albers)
    -Jdlon0/lat0/lat1/lat2/scale (Equidistant)
    -Jllon0/lat0/lat1/lat2/scale (Lambert)

    MISCELLANEOUS PROJECTIONS:

    -Jhlon0/scale (Hammer)
    -Jilon0/scale (Sinusoidal)
    -Jk[f|s]lon0/scale (Eckert IV (f) and VI (s))
    -Jnlon0/scale (Robinson)
    -Jrlon0/scale (Winkel Tripel)
    -Jvlon0/scale (Van der Grinten)
    -Jwlon0/scale (Mollweide)

    NON-GEOGRAPHICAL PROJECTIONS:

    -Jp[a]scale[/origin] (polar (theta,r) coordinates, optional a for azimuths and offset theta [0])
    -Jxx-scale[l|ppow][/y-scale[l|ppow]][d] (Linear, log, and power scaling)
    More details can be found in the psbasemap man pages.

-R  xmin, xmax, ymin, and ymax specify the Region of interest. For geographic regions, these limits correspond to west, east, south, and north and you may specify them in decimal degrees or in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left and upper right map coordinates are given instead of wesn. The two shorthands -Rg -Rd stand for global domain (0/360 or -180/+180 in longitude respectively, with -90/+90 in latitude). For calendar time coordinates you may either give relative time (relative to the selected TIME_EPOCH and in the selected TIME_UNIT; append t to -JX|x), or absolute time of the form [date]T[clock] (append T to -JX|x). At least one of date and clock must be present; the T is always required. The date string must be of the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or yyyy[-Www[-d]] (ISO week calendar), while the clock string must be of the form hh:mm:ss[.xxx]. The use of delimiters and their type and positions must be as indicated (however, input/output and plotting formats are flexible).

OPTIONS
No space between the option flag and the associated arguments.

-A  Give - to disable all annotations. The optional labelinfo controls the specifics of the label formatting and consists of a concatenated string made up of any of the following control arguments:
    +aangle for annotations at a fixed angle, +an for line-normal, or +ap for line-parallel [Default].
    +cdx[/dy] sets the clearance between label and optional text box. Append c|i|m|p to specify the unit or % to indicate a percentage of the label font size [15%].
    +ffont sets the desired font [Default ANNOT_FONT_PRIMARY].
    +g[color] selects opaque text boxes [Default is transparent]; optionally specify the color [Default is PAGE_COLOR].
    +jjust sets label justification [Default is CM].
    +kcolor sets color of text labels [Default is COLOR_BACKGROUND].
    +llabel sets the constant label text.
    +Llflag sets the label text according to the specified flag:
    flag is h: Take the label from the current multisegment header (first scan for an embedded -Llabel option, if not use the first word following the segment flag).
    flag is d: Take the Cartesian plot distances along the line as the label; append c|i|m|p as the unit [Default is MEASURE_UNIT].
    flag is D: Calculate actual map distances; append d|e|k|m|n as the unit [Default is d(egrees), unless label placement was based on map distances along the lines in which case we use the same unit specified for that algorithm]. Requires a map projection to be used.
    flag is f: Use text after the 2nd column in the fixed label location file as the label. Requires the fixed label location setting.
    flag is x: As h but use the headers in the xfile.d instead. Requires the crossing file option.
    +o selects rounded rectangular text box [Default is rectangular]. Not applicable for curved text (+v) and only makes sense for opaque text boxes.
    +p[pen] draws the outline of text boxsets [Default is no outline]; optionally specify pen for outline [Default is width = 0.25p, color = black, texture = solid].
    +rmin_rad will not place labels where the line's radius of curvature is less than min_rad [Default is 0].
    +ssize sets the desired font size in points [Default is 9].
    +uunit appends unit to all line labels. If unit starts with a leading hypen (-) then there will be no space between label value and the unit. [Default is no unit].
    +v specifies curved labels following the path [Default is straight labels].
    +w specifies how many (x, y) points will be used to estimate label angles [Default is 10].
    +=prefix prepends prefix to all line labels. If prefix starts with a leading hypen (-) then there will be no space between label value and the prefix. [Default is no prefix].

-B  Sets map boundary annotation and tickmark intervals; see the psbasemap man page for all the details.

-D  Dump the (x,y,z) coordinates of each contour to separate files, one for each contour segment. The files will be named dumpfile_cont_segment[_i].xyz, where cont is the contour value and segment is a running segment number for each contour interval (for closed contours we append _i.) However, when -M is used in conjunction with -D a single multisegment file is created instead.

-E  Sets the view point by specifying azimuth and elevation in degrees. [Default is 180/90].

-G  Controls the placement of labels along the contours. Choose among five controlling algorithms:
    -Gddist[c|i|m|p] or -GDdist[d|e|k|m|n]. For lower case d, give distances between labels on the plot in your preferred measurement unit c (cm), i (inch), m (meter), or p (points), while for upper case D, specify distances in map units and append the unit; choose among e (m), k (km), m (mile), n (nautical mile), or d (spherical degree). [Default is 10c or 4i].
    -Gfffile.d reads the ascii file ffile.d and places labels at locations in the file that matches locations along the contours. Inexact mathces and points outside the region are skipped.
    -Gl|Lline1[,line2,...] Give start and stop coordinates for one or more comma-separated straight line segments. Labels will be placed where these lines intersect the contours. The format of each line specification is start/stop, where start and stop are either a specified point lon/lat or a 2-character XY key that uses the justification format employed in pstext to indicate a point on the map, given as [LCR][BMT]. -GL will interpret the point pairs as defining great circles [Default is straight line].
    -Gnn_label specifies the number of equidistant labels for contours line [1]. Upper case -GN starts labeling exactly at the start of the line [Default centers them along the line]. -GN-1 places one justified label at start, while -GN+1 places one justified label at the end of contours. Optionally, append /min_dist[c|i|m|p] to enforce that a minimum distance separation between successive labels is enforced.
    -Gx|Xxfile.d reads the multi-segment file xfile.d and places labels at the intersections between the contours and the lines inxfile.d. -GX will resample the lines first along great-circle arcs.

-H  Input file(s) has Header record(s). Number of header records can be changed by editing your .gmtdefaults4 file. If used, GMT default is 1 header record. Use -Hi if only input data should have header records [Default will write out header records if the input data have them].

-I  Color the triangles using the color palette table.

-K  More PostScript code will be appended later [Default terminates the plot system].

-L  Draw the underlying triangular mesh using the specified pen attributes [Default is no mesh].

-M  When used in conjunction with -D a single multisegment file is created, and each contour section is preceded by a header record whose first column is flag followed by the contour level.

-N  Do NOT clip contours or image at the boundaries [Default will clip to fit inside region -R].

-O  Selects Overlay plot mode [Default initializes a new plot system].

-P  Selects Portrait plotting mode [GMT Default is Landscape, see gmtdefaults to change this].

-S  Skip all input xyz points that fall outside the region [Default uses all the data in the triangulation].

-T  Give name of file with network information. Each record must contain triplets of node numbers for a triangle [Default computes these using Delaunay triangulation (see triangulate)].

-U  Draw Unix System time stamp on plot. User may specify where the lower left corner of the stamp should fall on the page relative to lower left corner of plot. Optionally, append a label, or c (which will plot the command string.). The GMT parameters UNIX_TIME and UNIX_TIME_POS can affect the appearance; see the gmtdefaults man page for details.

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

-W  Select contouring and set contour pen attributes. If the + flag is set then the contour lines are colored according to the cpt file (see -C).

-X -Y
    Shift origin of plot by (x-shift,y-shift). Prepend a for absolute coordinates; the default (r) will reset plot origin. Give c to center plot using current page size.

-c  Specifies the number of plot copies. [Default is 1].

-:  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 affects both].

-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 3 input columns]. Use 4-byte integer triplets for node ids (-T).

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

EXAMPLES
To make a raw contour plot from the file topo.xyz and drawing the contours (pen = 2) given in the color palette file topo.cpt on a Lambert map at 0.5 inch/degree along the standard parallels 18 and 24, use

pscontour topo.xyz -R320/330/20/30 -Jl18/24/0.5i -Ctopo.cpt -W0.5p > topo.ps

To create a color PostScript plot of the numerical temperature solution obtained on a triangular mesh whose node coordinates and temperatures are stored in temp.xyz and mesh arrangement is given by the file mesh.ijk, using the colors in temp.cpt, run

pscontour temp.xyz -R0/150/0/100 -Jx0.1 -Ctemp.cpt -G -W0.25p > temp.ps

BUGS
Sometimes there will appear to be thin lines of the wrong color in the image. This is a round-off problem which may be remedied by using a higher value of DOTS_PR_INCH in the .gmtdefaults4 file.

SEE ALSO
gmt(1), grdcontour(1), grdimage(1), nearneighbor(1), psbasemap(1), psscale(1), surface(1), triangulate(1)

REFERENCES
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.
www.cs.cmu.edu/~quake/triangle.html