It is possible with Gifa to display different planes extracted from the 3D data-set, but also to display the 3D data-set as a volume in a 3D manner.
Plotting planes extracted from a 3D consists simply in selecting planes with the PLANE command, and plotting them as 2D with PLOT. For instance the simple macro :
for i = 1 to $si1_3d
plane F1 $i plot *pl title ("plane #"; $i) *pl page *pl
endfor
would do the job.
You can also check the more developed macro : plot_plane_3d distributed with the program.
It is possible to display 3D pictures of 3D data set. The principle is to draw a series of contour plots for each axes in a 3D space. This kind of display is useful for checking the quality of a 3D data-set, and also for making nice pictures.
DISP3D will open a window devoted to 3D display. No picture is displayed when opening because of the time a 3D display usually takes to compute. Unlike the 1D and 2D display, the 3D display must be forced with the REF3D command, and will remain unchanged even if the data or the parameters are changed. As usual ^C permits to stop the 3D display being computed.
This commands determine the aspect of the 3D display. The volume size is described by the CX, CY, CZ contexts. When opening the 3D window the size is taken to be equal to the largest of the 3 contexts. ALPHA, BETA and GAMA are the angles which describe the view point. AXIS3D determines which planes will be contoured. A value of F123 describes a complete contour, but simpler display (and faster) may be chosen. Usually a F1 value is the fastest choice. ZNOT is the focal with which the volume is displayed. A large value corresponds to a "tele" position, a small value to a "wide". OFFSET3D determines the position of the 0 point, values range from 0 to 1. SCALE3D is a scaling factor applied to the final image.
All these parameters can be easily entered and checked with the DISP3D? macro. An interactive, graphical mode is provided with the command CHECK3D, which display interactively an empty cube, thus permitting to modify the main ones.
Buttons are available with the CHECK3D command, which permits to directly choose some typical points of view (along each axis, along the main 3D diagonal of the cube). See above the definition of the box in the Graphic User Interface manual part.
This command generate on a plot file a plot equivalent to the display obtained with the REF3D command. The plot file must then be closed with the PAGE command, see the chapter on plotting.