These crescent shaped dunes appear on Earth and Mars. The TV program "What on Earth?" showed a magnetic one in Africa, with dark sand, probably of volcanic origin.

A recent paper has the Math, and a good summary:

https://arxiv.org/pdf/cond-mat/0308100.pdf

The cosine bump formula is in Fig. 6, and should be easy to do in nodeeditor.

Now needed is numeric simulation javascript software which outputs to MoI NURBS :-)

- Brian

Cosine Bump .nod file.
A pile of sand, 2 by 2 by 1 unit high.
Different lighting settings yield various "shadows."
Divisor of 4 yields PI/2, so the base is planar for that case.
Height scale of 10 caused "hangup" of MoI/Nodeeditor. (Did not wait for resolution.)
Trying to cross connect object connections in Nodeeditor caused "hangup" of MoI/Nodeeditor. (Did not wait for resolution.)
There are actually such things as "bump functions." q.v.

Very cool!