GNUPlot Manual
GNUPlot Manual
GNUPlot Manual
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36 SET-SHOW gnuplot 4.0 83<br />
independent. This can be used for 4d data drawing.<br />
Other notes:<br />
1. The term ’scan’ referenced above is used more among physicists than the term ’iso curve’ referenced<br />
in gnuplot documentation and sources. You measure maps recorded one scan after another scan, that’s<br />
why.<br />
2. The ’gray’ or ’color’ scale is a linear mapping of a continuous variable onto a smoothly varying palette<br />
of colors. The mapping is shown in a rectangle next to the main plot. This documentation refers to this<br />
as a "colorbox", and refers to the indexing variable as lying on the colorbox axis. See set colorbox<br />
(p. 60), set cbrange (p. 154).<br />
3. To use pm3d coloring to generate a two-dimensional plot rather than a 3D surface, use set view<br />
map or set pm3d map.<br />
Syntax:<br />
set pm3d<br />
set pm3d {<br />
}<br />
show pm3d<br />
unset pm3d<br />
{ at }<br />
{ scansautomatic | scansforward | scansbackward }<br />
{ flush { begin | center | end } }<br />
{ ftriangles | noftriangles }<br />
{ clip1in | clip4in }<br />
{ corners2color { mean|geomean|median|c1|c2|c3|c4 } }<br />
{ hidden3d | nohidden3d }<br />
{ implicit | explicit }<br />
{ map }<br />
Setting set pm3d (i.e. without options) sets up the default values. Otherwise, the options can be given<br />
in any order.<br />
Color surface can be drawn at the base or top (then it is a gray/color planar map) or at z-coordinates of<br />
surface points (gray/color surface). This is defined by the at option with a string of up to 6 combinations<br />
of b, t and s. For instance, at b plots at bottom only, at st plots firstly surface and then top map,<br />
while at bstbst will never by seriously used.<br />
Colored quadrangles are plotted one after another. When plotting surfaces (at s), the later quadrangles<br />
overlap (overdraw) the previous ones. (Gnuplot is not virtual reality tool to calculate intersections of<br />
filled polygon meshes.) You may try to switch between scansforward and scansbackward to force the<br />
first scan of the data to be plotted first or last. The default is scansautomatic where gnuplot makes a<br />
guess about scans order.<br />
If two subsequent scans do not have same number of points, then it has to be decided whether to<br />
start taking points for quadrangles from the beginning of both scans (flush begin), from their ends<br />
(flush end) or to center them (flush center). Note, that flush (center|end) are incompatible with<br />
scansautomatic: if you specify flush center or flush end and scansautomatic is set, it is silently<br />
switched to scansforward.<br />
If two subsequent scans do not have the same number of points, the option ftriangles specifies whether<br />
color triangles are drawn at the scan tail(s) where there are not enough points in either of the scan. This<br />
can be used to draw a smooth map boundary.<br />
Clipping with respect to x, y coordinates of quadrangles can be done in two ways. clip1in: all 4 points<br />
of each quadrangle must be defined and at least 1 point of the quadrangle must lie in the x and y ranges.<br />
clip4in: all 4 points of each quadrangle must lie in the x and y ranges.<br />
There is a single gray/color value associated to each drawn pm3d quadrangle (no smooth color change<br />
among vertices). The value is calculated from z-coordinates from the surrounding corners according<br />
to corners2color . The options ’mean’ (default), ’geomean’ and ’median’ produce various<br />
kinds of surface color smoothing. This may not be desired for pixel images or for maps with sharp<br />
and intense peaks, in which case the options ’c1’, ’c2’, ’c3’ or ’c4’ can be used instead to assign the