Take a Stroll in Another World

Another World II is a print by the famous Dutch artist M. C. Escher, depicting a cube with arch-like openings on each side. What makes the print interesting is that the depicted views in the arches are inconsistent, leaving the spectator puzzled as to the " impossible assembly " of views from different perspectives. In our work we invite the reader – and more so, the user of our software – to explore the strange geometry of this work by flying through a virtual Another World. The rendering of the inconsistent views is achieved by applying Portal Rendering. We point out the novelty of our work with respect to previous 3D computer models of different " impossible worlds " by M. C. Escher. We also suggest potential application contexts beyond the straightforward 3D reconstruction of Another World. 1. Another world Another World II (figure 1) [Ern76, esc07] is a print by the Dutch artist M. C. Escher. This intriguing work depicts a cube, with six architectural arches opening onto a moon-like landscape. However, the views through the arches are inconsistent. One can derive the relative position of the cube and the moon based on for example what is seen through the left opening , but then the view through the bottom opening is not the one that is expected: instead of looking down to the surface with craters, we see the sky. It is easy to notice that there are three views altogether, and pairs of neighboring arches share a common view. These pairs are cleverly placed on two adjacent sides of the cube, using altogether five sides. The sixth side, facing the observer has been removed entirely, making it possible to see the views through the arches without obstructions. Escher solved the problem of arranging six arches on five sides by placing two narrow arches on the right side and a single, wide arch on each of the other four sides. The arches are drawn according to the outside view of the moon. This of course makes the cube a very strange architectural piece, which is especially apparent on the right side, where two narrow arches are aligned " with head to bottom " next to each other. One experiences a certain dizziness from observing the three inconsistent views squeezed into a single scene. On the other hand, the airy openings, the uninhabited landscape and even the statues of …