Reads in a 2D data set for the ground magnetic field $B_x$ in form of a 3x1152 text file, transforms the data points onto CGM coordinates, constructs an annotated CGM coordinate mesh calculates a set of contour lines, and colors the 2D plot with a stepped colormap.
The page {Import} obtains the 2D data set, feeds it through the coordinate transformation, and triangulates the scattered points to generate the plot.