I mean the first Image linked in the last post before mine.
is this effect generally caused by hard-shadows as there is no softening?
I've read some articles about soft-shadows but if I remember right those did some arbitrary blurring of the shadow-edges that did not try to take the distances between the light and the shadow-caster and the one between the shadow-caster and the shadowed surface into account.
The thought is that the blurring would have to be based on 1. the light's area/volume 2. the distance between the light and the shadow caster (those two will alledgedly be influencing the blurring at most) and 3. the distance between the shadow caster and the shadowed surface as when crossing a medium light will diffute further.
EDIT: With jumping out of the plane I mean the shadow cast onto the larger box. The shadow seems to have a depth on it's right side