Quoting from the article: "A significant part of the problem was figuring out exactly what distortion Escher had used to blow up the centre of the picture; fir

Quoting from the article: "A significant part of the problem was figuring out exactly what distortion Escher had used to blow up the centre of the picture; firstly because we wanted to "undistort" the picture in order to be able to copy the townscape, and secondly so that we could transform our final photograph into something that looked like Escher's print." ... "Our eventual solution was to take a number of separate shots, zooming in on distinct parts of the model, and glue them together as a mosaic panorama. The image above was constructed in this way from 16 images. The final Escher transformation was implemented in a custom C program that I hacked together."