CNT3DX is a simple 3-d contour plotting routine. The input consists of a 2 dimensional grid of y values. The height of plotted contours relative to the y axis is calibrated to z axis so that scale can be taken from the plot. No perspective is used.
Options exist to vary the plotting angle and to plot axes.
Origin of the plot is in the lower-left corner. The x axis runs plotted left to right along the plot bottom. The y axis is plotted as a vertical displacement offset by the z axis value. The z axis appears to point into the screen. This gives the illusion of depth in the plot.