NAME¶
grdvector - Plot vector fields from grdfiles
SYNOPSIS¶
grdvector compx.grd compy.grd -Jparameters [
-A ] [
-Btickinfo ] [
-Ccptfile ] [
-E ] [
-Gfill] [
-Ix_inc[
m|c][/
y_inc[
m|c]] ] [
-K ]
[
-N ] [
-O ] [
-P ] [
-Qparameters ] [
-R west/east/south/north[
r] ] [
-S[
l]
scale ] [
-T ] [
-U[
/dx/dy/][
label] ] [
-V ] [
-Wcontourpen ] [
-Xx-shift ] [
-Yy-shift ] [
-Z ] [
-ccopies ]
DESCRIPTION¶
grdvector reads two 2-D gridded files which represents the x- and
y-components of a vector field and produces a vector field plot by drawing
vectors with orientation and length according to the information in the files.
Alternatively, polar coordinate components may be used (r, theta).
grdvector is basically a short-hand for using 2 calls to
grd2xyz
and pasting the output through
psxy -SV.
- compx.grd
- Contains the x-component of the vector field.
- compy.grd
- Contains the y-component of the vector field.
- -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 .gmtdefaults, but this can be overridden on the
command line by appending the c, i, or m to the scale/width value.
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]]
(Linear, log, and power scaling)
More details can be found in the psbasemap manpages.
OPTIONS¶
No space between the option flag and the associated arguments.
- -A
- Means grdfiles have polar (r, theta) components instead of Cartesian (x,
y).
- -B
- Sets map boundary tickmark intervals. See psbasemap for
details.
- -C
- Use cptfile to assign colors based on vector length.
- -E
- Center vectors on grid nodes [Default draws from grid node].
- -G
- Sets color or shade for vector interiors [Default is no fill]. Specify the
shade (0-255) or color (r/g/b, each in 0-255).
- -I
- Only plot vectors at nodes every x_inc, y_inc apart (must be
multiples of original grid spacing). Append m for minutes or
c for seconds. [Default plots every node].
- -K
- More PostScript code will be appended later [Default terminates the
plot system].
- -N
- Do NOT clip vectors at map boundaries [Default will clip].
- -bo
- Selects binary output. Append s for single precision [Default is
double].
- -P
- Selects Portrait plotting mode [GMT Default is Landscape, see
gmtdefaults to change this].
- -Q
- Select vector plot [Default is stick-plot]. Optionally, specify
parameters which are arrowwidth/headlength/headwidth
[Default is 0.075 c/0.3c/0.25c (or
0.03i/0.12i/0.1i)]. Append nsize which will
cause vectors shorter than size to have their appearence scaled by
length/ size.
- -R
- west, east, south, and north specify the Region of interest.
To specify boundaries in degrees and minutes [and seconds], use the
dd:mm[:ss] format. Append r if lower left and upper right map
coordinates are given instead of wesn. Specify a subset of the grid.
- -S
- Sets scale for vector length in data units per distance measurement unit
[1]. Append c, i, m, p to indicate the measurement unit (cm, inch, m,
point). Prepend l to indicate a fixed length for all vectors.
- -T
- Means azimuth should be converted to angles based on the selected map
projection.
- -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
- Set pen attributes used for vector outlines [Default: width = 1, color =
0/0/0, texture = solid].
- -X -Y
- Shift origin of plot by (x-shift,y-shift). Prepend a for
absolute coordinates; the default ( r) will reset plot origin.
- -Z
- Means the angles provided are azimuths rather than direction (requires
-A).
- -c
- Specifies the number of plot copies. [Default is 1]
EXAMPLES¶
To draw the vector field given by the files r.grd and theta.grd on a linear plot
with scale 5 cm per data unit, using vector rather than stick plot, and scale
vector magnitudes so that 10 units equal 1 inch, try
grdvector r.grd theta.grd
-Jx5
c -Q -S10
i >
gradient.ps
SEE ALSO¶
gmt(1gmt),
grdcontour(1gmt),
psxy(1gmt)