Well, I was just finishing up an old GrafX2 script for altitude mapping images - that is, giving an image an isometric projection and offsetting the pixels (depending on brightness) to produce a sense of depth. In order to make the scenes solid (rather than plotted) vertical lines are drawn to fill any gaps between altitude levels. It's quite basic and uneventful.

This fractal cloud image:


Would turn into this...


Now, for fun I tried it on this cloudfractal with plain rectangles and dividing lines visible.


And this popped out...


Note that there is no 3D, lightsourcing, color-calculations or any fancy stuff taking place. Just a few offset pixels and straight lines draw. As it happens the gap-filling lines uses the colors of the (shaded) dividing lines, which becomes the sides of the isometric structures. Nice surprise! :)