A <a href="https://en.wikipedia.org/wiki/Menger_sponge" class="extiw" title="en:Menger sponge">Menger sponge</a> with <a href="https://en.wikipedia.org/wiki/ray_tracing_(graphics)" class="extiw" title="en:ray tracing (graphics)">ray tracing</a>. In the sponge-center is a light source. The image illustrates the functionality of ray tracing by computers and the resulting shadow position and orientation. The bottom touches on the Menger sponge. The light is dimmed, so that the shadow effects take visual effect. A reflection at the vertical axis, going through the image center, offers, that the rendering is accurate, because symmetry is given.
<a href="//commons.wikimedia.org/wiki/User:PantheraLeo1359531" title="User:PantheraLeo1359531">PantheraLeo1359531</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>