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.