Molecular wallpaper ------------------- This picture is generated using a variant of the fisheye lens. The front of the picture is mapped into a circle by a 180 lens. The circle is then deformed into a square. The T, L, R and # indicate the Top, Left, Right and bottom of the front. *** ******* * T * * T * *L R* ==> *L R* * B * * B * *** ******* The same operation is performed on the back of the picture. ### ####### # T # # T # #L R# ==> #L R# # B # # B # ### ####### These two basic parts may now be pasted together in a chessboard pattern, care being taken to join top front = top back bottom front = bottom back left front = right back right front = left back. ******* ####### ******* ####### * B * # B # * B * # B # *R L* #L R# *R L* #L R# * T * # T # * T * # T # ******* ####### ******* ####### ####### ******* ####### ******* # T # * T * # T # * T * #R L# *L R* #R L# *L R* # B # * B * # B # * B * ####### ******* ####### ******* ******* ####### ******* ####### * B * # B # * B * # B # *R L* #L R# *R L* #L R# * T * # T # * T * # T # ******* ####### ******* ####### ####### ******* ####### ******* # T # * T * # T # * T * #R L# *L R* #R L# *L R* # B # * B * # B # * B * ####### ******* ####### ******* The sides of the front and back join in a proper manner. There is however a hiccup at the corners of the squares. The WINSOM model setup for the picture was PTYPE(3); NPICS(1); EYEDIST(-0.5); PTYPE(3) defined the squared fisheye lens. NPICS(1) created one complete pattern. L* #L R# *R T * # T # * T **** ####### **** #### ******* #### T # * T * # T L# *L R* #R B # * B * # B #### ******* #### **** ####### **** B * # B # * B L* #L R# *R This can be replicated as much as required without further rotation or mirroring. EYEDIST(-0.5) placed the viewer in the middle of the model.