The Grauniad ran this photo (mea scana culpa) of a cute installation the other week, which was just like a concept of symmetries causing irregular-seeming sampling effects (you could say Aliasing, or Moiré effects) in a solar spectrometer I've been working on recently.
When we consider this map and the grid of available ADC coordinate pairs that it represents, we can see that the observed nonuniformities in the position space resemble the optical effect that is seen when driving near a field of regularly spaced plants, military gravestones or other objects. Along certain directions of view, clear corridors seem to open up before us. In other directions we perceive an unbroken mass of objects. The angles along which we see a lower apparent density of objects are those where there is close alignment of our view angle and the symmetry of the grid. These are analogous to the locations of spikes and notches in the spectrum data.
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