PSBASEMAP

psbasemap − To plot PostScript basemaps

psbasemap −B[p|s]parameters −Jparameters −Rwest/east/south/north[/zmin/zmax][r] [ −Eazimuth/elevation ] [ −Gfill ] [ −Jz|Zparameters ] [ −K ] [ −L[f][x]lon0/lat0[/slon]/slat/length[m|n|k][:label:just][+ppen][+ffill] ] ] [ −O ] [ −P ] [ −U[/dx/dy/][label] ] [ −T[f|m][x]lon0/lat0/size[/info][:w,e,s,n:][+gint[/mint]] ] [ −V ] [ −X[a|c|r][x-shift[u]] ] [ −Y[a|c|r][y-shift[u]] ] [ −Zzlevel ] [ −ccopies ]

psbasemap creates PostScript code that will produce a basemap. Several map projections are available, and the user may specify separate tickmark intervals for boundary annotation, ticking, and [optionally] gridlines. A simple map scale or directional rose may also be plotted.

No space between the option flag and the associated arguments. Use upper case for the option flags and lower case for modifiers.

−B

Sets map boundary annotation and tickmark intervals. The format of tickinfo is [p|s]xinfo[/yinfo[/zinfo]][:."Title":][W|w][E|e][S|s][N|n][Z|z[+]]. The leading p [Default] or s selects the primary or secondary annotation information. Each of the ?info segments are textstrings of the form info[:"Axis label":][:="prefix":][:,"unit label":]. The info string is made up of one or more concatenated substrings of the form [which]stride[+-phase][u]. The optional which can be either a for annotation tick spacing [Default], f for frame tick spacing, and g for gridline spacing. If frame interval is not set, it is assumed to be the same as annotation interval. stride is the desired stride interval. The optional phase shifts the annotation interval by that amount. The optional u indicates the unit of the stride and can be any of Y (year, plot with 4 digits), y (year, plot with 2 digits), O (month, plot using PLOT_DATE_FORMAT), o (month, plot with 2 digits), U (ISO week, plot using PLOT_DATE_FORMAT), u (ISO week, plot using 2 digits), r (Gregorian week, 7-day stride from start of week TIME_WEEK_START), K (ISO weekday, plot name of day), D (date, plot using PLOT_DATE_FORMAT), d (day, plot day of month 0-31 or year 1-366, via PLOT_DATE_FORMAT), R (day, same as d, aligned with TIME_WEEK_START), H (hour, plot using PLOT_CLOCK_FORMAT), h (hour, plot with 2 digits), M (minute, plot using PLOT_CLOCK_FORMAT), m (minute, plot with 2 digits), C (second, plot using PLOT_CLOCK_FORMAT), c (second, plot with 2 digits). Note for geographic axes m and c instead mean arc minutes and arc seconds. All entities that are language-specific are under control by TIME_LANGUAGE. To specify separate x and y ticks, separate the substrings that apply to the x and y axes with a slash [/] (If a 3-D basemap is selected with −E and −Jz, a third substring pertaining to the vertical axis may be appended.) For linear/log/power projections (−Jx|X): Labels for each axis can be added by surrounding them with colons. If the first character in the label is a period, then the label is used as plot title; if it is a comma then the label is appended to each annotation; if it is an equal sign (=) the the prefix is prepended to each annotation (start label/prefix with - to avoid space between annotation and item); else it is the axis label. If the label consists of more than one word, enclose the entire label in double quotes (e.g., :"my label":).

By default, all 4 boundaries are plotted (referred to as W, E, S, N). To change the default, append the code for only those axes you want (e.g., WS for standard lower-left x- and y-axis system). Upper case (e.g., W) means draw axis/tickmarks AND annotate it, whereas lower case (e.g., w) will only draw axis/tickmarks. (If a 3-D basemap is selected with −E and −Jz, append Z or z to control the appearance of the vertical axis. Append ’+’ to draw the outline of the cube defined by −R. Note that for 3-D views the title, if given, will be suppressed.)
For non-geographical projections: Give negative scale (in −Jx) or axis length (in −JX) to change the direction of increasing coordinates (i.e., to make the y-axis positive down). For log10 axes: Annotations can be specified in one of three ways: (1) stride can be 1, 2, or 3. Annotations will then occur at 1, 1−2−5, or 1−2−3−4−...−9, respectively. This option can also be used for the frame and grid intervals. (2) An l is appended to the tickinfo string. Then, log10 of the tick value is plotted at every integer log10 value. (3) A p is appended to the tickinfo string. Then, annotations appear as 10 raised to log10 of the tick value. For power axes: Annotations can be specified in one of two ways: (1) stride sets the regular annotation interval. (2) A p is appended to the tickinfo string. Then, the annotation interval is expected to be in transformed units, but the annotation value will be plotted as untransformed units. E.g., if stride = 1 and power = 0.5 (i.e., sqrt), then equidistant annotations labeled 1−4−9... will appear.
These GMT parameters can affect the appearance of the map boundary: ANNOT_MIN_ANGLE, ANNOT_MIN_SPACING, ANNOT_FONT_PRIMARY, ANNOT_FONT_SECONDARY, ANNOT_FONT_SIZE_PRIMARY, ANNOT_FONT_SIZE_SECONDARY, ANNOT_OFFSET_PRIMARY, ANNOT_OFFSET_SECONDARY, BASEMAP_AXES, BASEMAP_FRAME_RGB, BASEMAP_TYPE, DEGREE_FORMAT, FRAME_PEN, FRAME_WIDTH, GRID_CROSS_SIZE_PRIMARY, GRID_PEN_PRIMARY, GRID_CROSS_SIZE_SECONDARY, GRID_PEN_SECONDARY, HEADER_FONT, HEADER_FONT_SIZE, LABEL_FONT, LABEL_FONT_SIZE, LINE_STEP, OBLIQUE_ANNOTATION, PLOT_CLOCK_FORMAT, PLOT_DATE_FORMAT, TIME_FORMAT_PRIMARY, TIME_FORMAT_SECONDARY, TIME_LANGUAGE, TIME_WEEK_START, TICK_LENGTH, TICK_PEN, and Y_AXIS_TYPE; see the gmtdefaults man page for details.

−J

Selects the map projection. The following character determines the projection. If the character is upper case then the argument(s) supplied as scale(s) is interpreted to be the map width (or axis lengths), else the scale argument(s) is the map scale (see its definition for each projection). 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 values. Append h, +, or - to the given width if you instead want to set map height, the maximum dimension, or the minimum dimension, respectively [Default is w for width].

The ellipsoid used in the map projections is user-definable by editing the .gmtdefaults4 file in your home directory. 63 commonly used ellipsoids and a spheroid are currently supported, and users may also specify their own ellipsoid parameters (see man gmtdefaults for more details). GMT default is WGS-84. Several GMT parameters can affect the projection: ELLIPSOID, INTERPOLANT, MAP_SCALE_FACTOR, and MEASURE_UNIT; see the gmtdefaults man page for details.
Choose one of the following projections (The E or C after projection names stands for Equal-Area and Conformal, respectively):

CYLINDRICAL PROJECTIONS:

−Jclon0/lat0/scale or −JClon0/lat0/width (Cassini).

Give projection center and scale (1:xxxx or UNIT/degree).

−Jclon0/lat0/scale or −JClon0/lat0/width (Cassini).

Give projection center and scale (1:xxxx or UNIT/degree).

−Jjlon0/scale or −JJlon0/width (Miller Cylindrical Projection).

Give the central meridian and scale (1:xxxx or UNIT/degree).

−Jmparameters (Mercator [C]).

Specify one of:

−Jmscale or −JMwidth

Give scale along equator (1:xxxx or UNIT/degree).

−Jmlon0/lat0/scale or −JMlon0/lat0/width

Give central meridian, standard latitude and scale along parallel (1:xxxx or UNIT/degree).

−Joparameters (Oblique Mercator [C]).

Specify one of:

−Joalon0/lat0/azimuth/scale or −JOalon0/lat0/azimuth/width

Set projection center, azimuth of oblique equator, and scale.

−Joblon0/lat0/lon1/lat1/scale or −JOblon0/lat0/lon1/lat1/scale

Set projection center, another point on the oblique equator, and scale.

−Joclon0/lat0/lonp/latp/scale or −JOclon0/lat0/lonp/latp/scale

Set projection center, pole of oblique projection, and scale.

Give scale along oblique equator (1:xxxx or UNIT/degree).

−Jqlon0/scale or −JQlon0/width (Equidistant Cylindrical Projection (Plate Carree)).

Give the central meridian and scale (1:xxxx or UNIT/degree).

−Jtparameters (Transverse Mercator [C]).

Specify one of:

−Jtlon0/scale or −JTlon0/width

Give the central meridian and scale (1:xxxx or UNIT/degree).

−Jtlon0/lat0/scale or −JTlon0/lat0/width

Give projection center and scale (1:xxxx or UNIT/degree).

−Juzone/scale or −JUzone/width (UTM - Universal Transverse Mercator [C]).

Give the zone number (1-60) and scale (1:xxxx or UNIT/degree).
Zones: prepend - or + to enforce southern or northern hemisphere conventions [northern if south > 0].

−Jylon0/lats/scale or −JYlon0/lats/width (Basic Cylindrical Projections [E]).

Give the central meridian, standard parallel, and scale (1:xxxx or UNIT/degree). The standard parallel is typically one of these (but can be any value):

45 - The Peters projection
37.4 - The Trystan Edwards projection
30 - The Behrman projection
0 - The Lambert projection

AZIMUTHAL PROJECTIONS:

Except for polar aspects, −Rw/e/s/n will be reset to −Rg. Use −R<...>r for smaller regions.

−Jalon0/lat0/scale or −JAlon0/lat0/width (Lambert [E]).

lon0/lat0 specifies the projection center. Give scale as 1:xxxx or radius/lat, where radius is distance in UNIT from origin to the oblique latitude lat.

−Jelon0/lat0/scale or −JElon0/lat0/width (Equidistant).

lon0/lat0 specifies the projection center. Give scale as 1:xxxx or radius/lat, where radius is distance in UNIT from origin to the oblique latitude lat.

−Jflon0/lat0/horizon/scale or −JFlon0/lat0/horizon/width (Gnomonic).

lon0/lat0 specifies the projection center. horizon specifies the max distance from projection center (in degrees, < 90). Give scale as 1:xxxx or radius/lat, where radius is distance in UNIT from origin to the oblique latitude lat.

−Jglon0/lat0/scale or −JGlon0/lat0/width (Orthographic).

lon0/lat0 specifies the projection center. Give scale as 1:xxxx or radius/lat, where radius is distance in UNIT from origin to the oblique latitude lat.

−Jslon0/lat0/scale or −JSlon0/lat0/width (General Stereographic [C]).

lon0/lat0 specifies the projection center. Give scale as 1:xxxx (true at pole) or slat/1:xxxx (true at standard parallel slat) or radius/lat (radius in UNIT from origin to the oblique latitude lat).

CONIC PROJECTIONS:

−Jblon0/lat0/lat1/lat2/scale or −JBlon0/lat0/lat1/lat2/width (Albers [E]).

Give projection center, two standard parallels, and scale (1:xxxx or UNIT/degree).

−Jdlon0/lat0/lat1/lat2/scale or −JDlon0/lat0/lat1/lat2/width (Equidistant)

Give projection center, two standard parallels, and scale (1:xxxx or UNIT/degree).

−Jllon0/lat0/lat1/lat2/scale or −JLlon0/lat0/lat1/lat2/width (Lambert [C])

Give origin, 2 standard parallels, and scale along these (1:xxxx or UNIT/degree).

MISCELLANEOUS PROJECTIONS:

−Jhlon0/scale or −JHlon0/width (Hammer [E]).

Give the central meridian and scale along equator (1:xxxx or UNIT/degree).

−Jilon0/scale or −JIlon0/width (Sinusoidal [E]).

Give the central meridian and scale along equator (1:xxxx or UNIT/degree).

−Jk[f|s]lon0/scale or −JK[f|s]lon0/width (Eckert IV (f) and VI (s) [E]).

Give the central meridian and scale along equator (1:xxxx or UNIT/degree).

−Jnlon0/scale or −JNlon0/width (Robinson).

Give the central meridian and scale along equator (1:xxxx or UNIT/degree).

−Jrlon0/scale −JRlon0/width (Winkel Tripel).

Give the central meridian and scale along equator (1:xxxx or UNIT/degree).

−Jvlon0/scale or −JVlon0/width (Van der Grinten).

Give the central meridian and scale along equator (1:xxxx or UNIT/degree).

−Jwlon0/scale or −JWlon0/width (Mollweide [E]).

Give the central meridian and scale along equator (1:xxxx or UNIT/degree).

NON-GEOGRAPHICAL PROJECTIONS:

−Jp[a]scale[/origin][r|z] or −JP[a]width[/origin][r|z] (Polar coordinates (theta,r))

Optionally insert a after −Jp [ or −JP] for azimuths CW from North instead of directions CCW from East [default]. Optionally append /origin in degrees to indicate an angular offset [0]). Finally, append r if r is elevations in degrees (requires s >= 0 and n <= 90) or z if you want to annotate depth rather than radius [Default]. Give scale in UNIT/r-unit.

−Jxx-scale[/y-scale] or −JXwidth[/height] (Linear, log, and power scaling)

Give x-scale in UNIT/x-unit and/or y-scale in UNIT/y-unit; or specify width and/or height in UNIT (y-scale=x-scale if not specified separately). Use negative scale(s) to reverse the direction of an axis (e.g., to have y be positive down). Optionally, append to x-scale, y-scale, width or height one of the following:

d

Data are geographical coordinates (in degrees).

l

Take log10 of values before scaling.

ppower

Raise values to power before scaling.

t

Input coordinates are time relative to TIME_EPOCH.

T

Input coordinates are absolute time.

Default axis lengths (see gmtdefaults) can be invoked using −JXh (for landscape); −JXv (for portrait) will swap the x- and y-axis lengths. The GMT default unit for this installation is UNIT. However, you may change this by editing your .gmtdefaults4 file(s) (run gmtdefaults to create one if you do not have it).

−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).

−E

Sets the viewpoint’s azimuth and elevation (for perspective view) [180/90].

−G

Paint inside of basemap. [Default is no fill]. Specify the grey shade (0−255) or color (r/g/b, each in range 0−255; h-s-v, ranges 0−360, 0−1, 0−1; or c/m/y/k, each in range 0−100%; or valid color name).

−Jz

Sets the vertical scaling (for 3-D maps). Same syntax as −Jx.

−K

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

−L

Draws a simple map scale centered on lon0/lat0. Use −Lx to specify x/y position instead. Scale is calculated at latitude slat (optionally supply longitude slon for oblique projections [Default is central meridian]), length is in km [miles if m is appended; nautical miles if n is appended]. Use −Lf to get a "fancy" scale [Default is plain]. The default label equals the distance unit (km, miles, nautical miles) and is justified on top of the scale [t]. Change this by giving your own label (or - to keep the default) and justification (l(eft), r(ight), t(op), b(ottom), and u(unit) - using the label as a unit appended to all distance annotations along the scale). If you want to place a rectangle behind the scale, specify pen and/or fill parameters with the +p and +f modifiers.

−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].

−T

Draws a simple map directional rose centered on lon0/lat0. Use −Tx to specify x/y position instead. The size is the diameter of the rose, and optional label information can be specified to override the default values of W, E, S, and N (Give :: to suppress all labels). The default [plain] map rose only labels north. Use −Tf to get a "fancy" rose, and specify what kind of rose you want drawn. The default [1] draws the two principal E-W, N-S orientations, 2 adds the two intermediate NW-SE and NE-SW orientations, while 3 adds the eight minor orientations WNW-ESE, NNW-SSE, NNE-SSW, and ENE-WSW. For a magnetic compass rose, specify −Tm. If given, info must be the two parameters dec/dlabel, where dec is the magnetic declination and dlabel is a label for the magnetic compass needle (specify ’-’ to format a label from dec). Then, both directions to geographic and magnetic north are plotted [Default is geographic only]. If the north label = * then a north star is plotted instead of the north label. Annotation and two levels of tick intervals for geographic and magnetic directions are 10/5/1 and 30/5/1 degrees, respectively; override these settings by appending +gints[/mints]. Color and pen attributes are taken from COLOR_BACKGROUND and TICK_PEN, respectively, while label fonts and sizes follow the usual annotation, label, and header font settings.

−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"].

−X −Y

Shift origin of plot by (x-shift,y-shift), and opetionally append units (c, i, m, p). Prepend a for absolute coordinates; the default (r) will reset plot origin. Give c to center plot using current page size.

−Z

For 3-D projections: Sets the z-level of the basemap [0].

−c

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

The following section illustrates the use of the options by giving some examples for the available map projections. Note how scales may be given in several different ways depending on the projection. Also note the use of upper case letters to specify map width instead of map scale.

Linear x-y plot

To make a linear x/y frame with all axes, but with only left and bottom axes annotated, using xscale = yscale = 1.0, ticking every 1 unit and annotating every 2, and using xlabel = "Distance" and ylabel = "No of samples", use

psbasemap −R0/9/0/5 −Jx1 −Bf1a2:Distance:/:"No of samples":WeSn > linear.ps

Log-log plot

To make a log-log frame with only the left and bottom axes, where the x-axis is 25 cm and annotated every 1-2-5 and the y-axis is 15 cm and annotated every power of 10 but has tickmarks every 0.1, run

psbasemap −R1/10000/1e20/1e25 −JX25cl/15cl −B2:Wavelength:/a1pf3:Power:WS > loglog.ps

Power axes

To design an axis system to be used for a depth−sqrt(age) plot with depth positive down, ticked and annotated every 500m, and ages annotated at 1 my, 4 my, 9 my etc, use

psbasemap −R0/100/0/5000 −Jx1p0.5/-0.001 −B1p:"Crustal age":/500:Depth: > power.ps

Polar (theta,r) plot

For a base map for use with polar coordinates, where the radius from 0 to 1000 should correspond to 3 inch and with gridlines and ticks every 30 degrees and 100 units, use

psbasemap −R0/360/0/1000 −JP6i −B30p/100 > polar.ps

Cassini

A 10-cm-wide basemap using the Cassini projection may be obtained by

psbasemap −R20/50/20/35 −JC35/28/10c −P −B5g5:.Cassini: > cassini.ps

Mercator [conformal]

A Mercator map with scale 0.025 inch/degree along equator, and showing the length of 5000 km along the equator (centered on 1/1 inch), may be plotted as

psbasemap −R90/180/-50/50 −Jm0.025i −B30g30:.Mercator: −Lx1i/1i/0/5000 > mercator.ps

Miller

A global Miller cylindrical map with scale 1:200,000,000 may be plotted as

psbasemap −R0/360/-90/90 −Jj180/1:200000000 −B30g30:.Miller: > miller.ps

Oblique Mercator [conformal]

To create a page-size global oblique Mercator basemap for a pole at (90,30) with gridlines every 30 degrees, run

psbasemap −R0/360/-70/70 −Joc0/0/90/30/0.064cd −B30g30:."Oblique Mercator": > oblmerc.ps

Transverse Mercator [conformal]

A regular Transverse Mercator basemap for some region may look like

psbasemap −R69:30/71:45/-17/-15:15 −Jt70/1:1000000 −B15m:."Survey area": −P > transmerc.ps

Equidistant Cylindrical Projection

This projection only needs the central meridian and scale. A 25 cm wide global basemap centered on the 130E meridian is made by

psbasemap −R-50/310/-90/90 −JQ130/25c −B30g30:."Equidistant Cylindrical": > cyl_eqdist.ps

Universal Transverse Mercator [conformal]

To use this projection you must know the UTM zone number, which defines the central meridian. A UTM basemap for Indo-China can be plotted as

psbasemap −R95/5/108/20r −Ju46/1:10000000 −B3g3:.UTM: > utm.ps

Basic Cylindrical [equal-area]

First select which of the cylindrical equal-area projections you want by deciding on the standard parallel. Here we will use 45 degrees which gives the Peters projection. A 9 inch wide global basemap centered on the Pacific is made by

psbasemap −R0/360/-90/90 −JY180/45/9i −B30g30:.Peters: > peters.ps

Albers [equal-area]

A basemap for middle Europe may be created by

psbasemap −R0/90/25/55 −Jb45/20/32/45/0.25c −B10g10:."Albers Equal-area": > albers.ps

Lambert [conformal]

Another basemap for middle Europe may be created by

psbasemap −R0/90/25/55 −Jl45/20/32/45/0.1i −B10g10:."Lambert Conformal Conic": > lambertc.ps

Equidistant

Yet another basemap of width 6 inch for middle Europe may be created by

psbasemap −R0/90/25/55 −JD45/20/32/45/6i −B10g10:."Equidistant conic": > econic.ps

Lambert [equal-area]

A 15-cm-wide global view of the world from the vantage point -80/-30 will give the following basemap:

psbasemap −R0/360/-90/90 −JA-80/-30/15c −B30g30/15g15:."Lambert Azimuthal": > lamberta.ps

Follow the instructions for stereographic projection if you want to impose rectangular boundaries on the azimuthal equal-area map but substitute −Ja for −Js.

Equidistant

A 15-cm-wide global map in which distances from the center (here 125/10) to any point is true can be obtained by:

psbasemap −R0/360/-90/90 −JE125/10/15c −B30g30/15g15:."Equidistant": > equi.ps

Gnomonic

A view of the world from the vantage point -100/40 out to a horizon of 60 degrees from the center can be made using the Gnomonic projection:

psbasemap −R0/360/-90/90 −JF-100/40/60/6i −B30g30/15g15:."Gnomonic": > gnomonic.ps

Orthographic

A global perspective (from infinite distance) view of the world from the vantage point 125/10 will give the following 6-inch-wide basemap:

psbasemap −R0/360/-90/90 −JG125/10/6i −B30g30/15g15:."Orthographic": > ortho.ps

Stereographic [conformal]

To make a Polar stereographic projection basemap with radius = 12 cm to −60 degree latitude, with plot title "Salinity measurements", using 5 degrees annotation/tick interval and 1 degree gridlines, run

psbasemap −R-45/45/-90/-60 −Js0/-90/12c/-60 −B5g5:."Salinity measurements": > stereo1.ps

To make a 12-cm-wide stereographic basemap for Australia from an arbitrary view point (not the poles), and use a rectangular boundary, we must give the pole for the new projection and use the −R option to indicate the lower left and upper right corners (in lon/lat) that will define our rectangle. We choose a pole at 130/-30 and use 100/-45 and 160/-5 as our corners. The command becomes

psbasemap −R100/-45/160/-5r −JS130/-30/12c −B30g30/15g15:."General Stereographic View": > stereo2.ps

Hammer [equal-area]

The Hammer projection is mostly used for global maps and thus the spherical form is used. To get a world map centered on Greenwich at a scale of 1:200000000, use

psbasemap −R0/360/-90/90 −Jh180/1:200000000 −B30g30/15g15:.Hammer: > hammer.ps

Sinusoidal [equal-area]

To make a sinusiodal world map centered on Greenwich, with a scale along the equator of 0.02 inch/degree, use

psbasemap −R-180/180/-90/90 −Ji0/0.02i −B30g30/15g15:."Sinusoidal": > sinus1.ps

To make an interrupted sinusiodal world map with breaks at 160W, 20W, and 60E, with a scale along the equator of 0.02 inch/degree, run the following sequence of commands:

psbasemap −R-160/-20/-90/90 −Ji-90/0.02i −B30g30/15g15Wesn −K > sinus_i.ps
psbasemap −R-20/60/-90/90 −Ji20/0.02i −B30g30/15g15wesn −O −K −X2.8i >> sinus_i.ps
psbasemap −R60/200/-90/90 −Ji130/0.02i −B30g30/15g15wEsn −O −X1.6i >> sinus_i.ps

Eckert IV [equal-area]

Pseudo-cylindrical projection typically used for global maps only. Set the central longitude and scale, e.g.,

psbasemap −R0/360/-90/90 −Jkf180/0.064c −B30g30/15g15:."Eckert IV": > eckert4.ps

Eckert VI [equal-area]

Another pseudo-cylindrical projection typically used for global maps only. Set the central longitude and scale, e.g.,

psbasemap −R0/360/-90/90 −Jks180/0.064c −B30g30/15g15:."Eckert VI": > eckert6.ps

Robinson

Projection designed to make global maps "look right". Set the central longitude and width, e.g.,

psbasemap −R-180/180/-90/90 −JN0/8i −B30g30/15g15:."Robinson": > robinson.ps

Winkel Tripel

Yet another projection typically used for global maps only. You can set the central longitude, e.g.,

psbasemap −R90/450/-90/90 −JR270/25c −B30g30/15g15:."Winkel Tripel": > winkel.ps

Mollweide [equal-area]

The Mollweide projection is also mostly used for global maps and thus the spherical form is used. To get a 25-cm-wide world map centered on the Dateline:

psbasemap −R0/360/-90/90 −JW180/25c −B30g30/15g15:.Mollweide: > mollweide.ps

Van der Grinten

The Van der Grinten projection is also mostly used for global maps and thus the spherical form is used. To get a 7-inch-wide world map centered on the Dateline:

psbasemap −R0/360/-90/90 −JV180/7i −B30g30/15g15:."Van der Grinten": > grinten.ps

For some projections, a spherical earth is implicitly assumed. A warning will notify the user if −V is set.

The −B option is somewhat complicated to explain and comprehend. However, it is fairly simple for most applications (see examples).

gmtdefaults(l), GMT(l)