in the book Mukarnas (ISBN 978-975-7618-64-5) Fatin Uluengin shows the transition from 2D to 3D.[br]From bottom to the top:[br][list][*]Upon the 2D plan cells are placed whose ground plane matches with the figures of the plan.[/*][*]These cellen form concentric circles.[/*][*]In 3D one puts these concentric circles one upon the other.[/*][/list]

Next applet shows dynamicly this transition from a plan to a 3D construction.