grdvector - Plot vector fields from grdfiles

grdvectorcompx.grdcompy.grd-Jparameters[-A] [-Btickinfo] [-Ccptfile] [-E] [-Gfill] [-Ix_inc[m|c][/y_inc[m|c]] ] [-K] [-N] [-O] [-P] [-Qparameters] [-Rwest/east/south/north[r] ] [-Sscale] [-T] [-U[/dx/dy/][label] ] [-V] [-Wcontourpen] [-Xx-shift] [-Yy-shift] [-Zzlevel] [-ccopies]

grdvectorreads 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).grdvectoris basically a short-hand for using 2 calls togrd2xyzand pasting the output throughpsxy-SV.compx.grdContains the x-component of the vector field.compy.grdContains the y-component of the vector field.-JSelects the map projection. Scale is inch/degree, 1:xxxxx, or width in inch (upper case modifier).CYLINDRICALPROJECTIONS:-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)-Juzone/scale(UTM - Universal Transverse Mercator)-Jylon0/lats/scale(Basic Cylindrical Projection)AZIMUTHALPROJECTIONS:-Jalon0/lat0/scale(Lambert).-Jelon0/lat0/scale(Equidistant).-Jflon0/lat0/horizon/scale(Gnomonic).-Jglon0/lat0/scale(Orthographic).-Jslon0/lat0/scale(General Stereographic)CONICPROJECTIONS:-Jblon0/lat0/lat1/lat2/scale(Albers)-Jllon0/lat0/lat1/lat2/scale(Lambert)MISCELLANEOUSPROJECTIONS:-Jhlon0/scale(Hammer)-Jilon0/scale(Sinusoidal)-Jklon0/scale(Eckert VI)-Jnlon0/scale(Robinson)-Jrlon0/scale(Winkel Tripel)-Jwlon0/scale(Mollweide)NON-GEOGRAPHICALPROJECTIONS:-Jpscale(Linear projection for polar (theta,r) coordinates)-Jxx-scale[l|ppow][/y-scale[l|ppow]] (Linear, log, and power scaling) More details can be found in thepsbasemapmanpages.

No space between the option flag and the associated arguments.-AMeans grdfiles have polar (r, theta) components instead of Cartesian (x, y).-BSets map boundary tickmark intervals. Seepsbasemapfor details.-CUsecptfileto assign colors based on vector length.-ECenter vectors on grid nodes [Default draws from grid node].-GSets color or shade for vector interiors [Default is no fill]. Specify the shade (0-255) or color (r/g/b), or-Gpdpi/pattern, wherepatterngives the number of the built-in pattern (1-90) OR the name of a Sun 1-, 8-, or 24-bit raster file.dpisets the resolution of the image. For 1-bit rasters: use-GPfor inverse video, or append:Fr/g/b[B[r/g/b]] to specify fore- and background colors. SeeGMTCookbook & Technical Reference Appendix E for information on individual patterns.-IOnly plot vectors at nodes everyx_inc,y_incapart (must be multiples of original grid spacing). Appendmfor minutes orcfor seconds. [Default plots every node].-KMorePostScriptcode will be appended later [Default terminates the plot system].-NDo NOT clip vectors at map boundaries [Default will clip].-OSelects Overlay plot mode [Default initializes a new plot system].-PSelects Portrait plotting mode [GMTDefault is Landscape, see gmtdefaults to change this].-QSelect vector plot [Default is stick-plot]. Optionally, specifyparameterswhich arearrowwidth/headlength/headwidth(in inch) [Default is 0.03i/0.12i/0.1i]. Append nsizewhich will cause vectors shorter thansizeto have their appearence scaled by length/size.-Rwest,east,south, andnorthspecify the Region of interest. To specify boundaries in degrees and minutes [and seconds], use the dd:mm[:ss] format. Appendrif lower left and upper right map coordinates are given instead of wesn. Specify a subset of the grid.-SSets scale for vector length in data units per inch [1].-TMeans azimuth should be converted to angles based on the selected map projection.-UDraw 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 in inch [Default is (-0.75i/- 0.75i)]. Optionally, append a label, orc(which will plot the command string.)-VSelects verbose mode, which will send progress reports to stderr [Default runs "silently"].-WSet pen attributes used for vector outlines [Default: width = 1, color = 0/0/0, texture = solid].-X-YShift origin of plot by (x-shift,y-shift) inch [Default is (a1i,a1i) for new plots, (0,0) for overlays]. Prependafor absolute coordinates; the default (r) will reset plot origin.-ZMeans the angles provided are azimuths rather than direction (requires-A).-cSpecifies the number of plot copies. [Default is 1]

To draw the vector field given by the files r.grd and theta.grd on a linear plot with scale 2 inch 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-Jx2i-Q-S0.1i> gradient.ps

gmt, grdcontour, psxy

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