There is nothing in a dune field to tell you how big anything is. No trees, no buildings, no horizon you can trust. For twenty minutes this was an abstract — two tones of orange meeting along a curve.
Then a line of figures crested the ridge and the whole frame snapped into proportion. They are roughly four hundred metres away. The dune is about the height of a fifteen-storey building.
I have a dozen frames of the same curve without them. None of them are photographs.