GPLOT recipes: Creating a simple colour plot

This colour plot is a PostScript copy of the GIDS-display, where a set was displayed with application VIEW. It shows contours and special (i.e. non-default) axis labeling.

The GPLOT macro:

First play with scales and labels in a X11 window to get sizes and labels right. Then select a Portrait Colour Postscript file with:
 device pcpsfile/
The commands listed below can be entered at the COMMAND= prompt manually or can be read from a command file with command input myfile.txt (or whatever you called your command file). The set is called model508seg and the subset is PARAM 7 (but the PARAM axis was the last axis of the set and we omitted the axis name). With command location the plot starts at 30 mm from the left and 20 mm from the bottom of the device (e.g. of the X11 window or the plot on paper). The command box without numbers assumes that you want to display the entire subset. Note that scaling needs to be specified in both x and y direction. Scales are in grids/mm. Instead of xscale and yscale, we used the size commands xsize and ysize.

 inset model508seg 7      ! Name of the input set and number of subset
 location 30 20           ! Origin of plot
 box                      ! Define limits of the frame
 xsize 120                ! Plot width is 120 mm
 ysize 85                 ! Plot height is 85 mm
 xmargin 2                ! 2 mm between plot and left or right axis
 ymargin 2                ! 2 mm between plot and top or bottom axis
 pause                    ! Press a key to continue executing
                          ! Not needed if commands are entered manually
If the above commands were read from a command file then GPLOT is pausing after pause (note that if commands are entered manually, pause is not necessary) and it is time to display your set with VIEW and adjust colours etc. in GIDS until you are satisfied with the result. At that moment the command getlut freezes the colours and colour scaling. The command colplot dumps the GIDS contents to the selected output device, But only if that device was is a so called PostScript colour printer or -file.

The colour dump must be made before drawing other things like contours, because in PostScript it is possible to plot text or lines over an existing colour or gray scale image, but the opposite is NOT true.
In this case the default axis labels were not satisfying so the starting position and the stepsize are selected with axdelta and axpos. The bottom axis is a Right Ascension axis. Therefore the step size is in hmssec instead of seconds of arc. Note that the axdelta and axpos commands are given BEFORE an axis command and the axtitle command AFTER an axis command.
 charhei 3                ! Character height 3 mm
 axdelta 20 HMSSEC        ! Step size for RA axis (20 hmssec = 20*15 arcsec)
 axpos * 10 16 0          ! Start main label at 10h16m0sec
 axformat hMS             ! Plot always minuts and seconds in RA labels
 axis bp                  ! Plot the bottom axis in physical coordinates
 axtitle                  ! Plot a title under the bottom axis
 axpos * 45 35 0          ! Dec axis start position 45d35m0s
 axdelta 5 arcmin         ! Major tick separation 5 min. of arc
 axis lp                  ! Label left axis with physical coordinates
 axtitle                  ! Default title for this axis
 axis t
 axis r
The contours and the title of the plot are plotted last. Plotting is finished only after the close command. The name of the created file is written in the log file.
 levels 10:120:20         ! Select countour levels 10 to 120, step 20
 conto                    ! Draw the contours
 font italic              ! Select italics font
 charhe 5                 ! Set char. height to 5 mm
 toplabel MODEL 18        ! Write label on top
 close                    ! Close the plot
The PostScript file resides on disk. Outside Hermes it can be inspected with GhostScript or GhostView and sent to a colour printer with a Unix command like:
 lpr -Pcps
It could have been sent directly to a colour printer if you selected:
 device pcpsfile