The fourier transform is the same for all time, and the time-series contains all frequencies, so it makes sense to plot them on orthogonal axes. However it makes sense for them to share the 3rd axis for magnitude.
However, the Im parts are just bolted on orthogonally to the Re parts and orthogonally to the magnitude. The reason the Im part of the time series shares an axis with frequency is just because the author ran out of dimensions.
However, the Im parts are just bolted on orthogonally to the Re parts and orthogonally to the magnitude. The reason the Im part of the time series shares an axis with frequency is just because the author ran out of dimensions.