Girih

Origins with curvilinear knot patterns The girih style of ornamentation is thought to have been inspired by 2nd century AD Syrian Roman knotwork patterns. Its mathematical patterns, structured around multiple lines of symmetry, are based on innovations in mathematics that occurred in the Islamic world after the ninth century. These had curvilinear interlaced strapwork with three-fold rotational symmetry. The Umayyad Mosque (709–715) in Damascus, Syria has window screens made of interlacing undulating strapwork in the form of six-pointed stars. Early examples of Islamic geometric patterns made of straight strap lines can be seen in the architecture of the surviving gateway of the Ribat-i Malik caravanserai, Uzbekistan, built in 1078. The wide application of girih in architecture reflects the close relationship between Islamic architecture, geometry, and craft. Architecture was classified in the field of practical geometry in the early Islamic period, and building projects always involve a muhandis (geometer). Early Islamic forms The earliest form of girih on a book is seen in the frontispiece of a Quran manuscript from the year 1000, found in Baghdad. It is illuminated with interlacing octagons and thuluth calligraphy. In woodwork, one of the earliest surviving examples of Islamic geometric art is the 13th-century minbar (pulpit) of the Mosque of Ibn Tulun, Cairo. Girih patterns can be created in woodwork in two different ways. In one, a wooden grille with polygons and stars is created; the holes can be left as they are, or filled with some material. In the other, called gereh-chini small wooden panels of geometric shapes are created individually, and combined to create an elaborate design. This book laid the groundwork for designing girih by explaining fundamental grammar for construction girih patterns. In the same period, artisans compiled girih pattern books such as the Topkapı Scroll. While curvilinear precedents of girih were seen in the 10th century, fully developed girih patterns were not seen before the 11th century in Iran. It became a dominant design element in the 11th and 12th centuries, as in the carved stucco panels with interlaced girih of the Kharraqan towers (1067) near Qazvin, Iran. Stylized plant decorations were sometimes co-ordinated with girih. After the Safavid period, the use of girih continued in the Seljuq dynasty and the Ilkhanate. In the 14th century, girih became a minor element in the decorative arts; it was largely replaced by vegetal patterns during the Timurid dynasty, but continued to be important in decorative arts in Central Asian monuments after that time. ==Construction==

Compass and straight edge Girih consists of geometric designs, often of stars and polygons, which can be constructed in a variety of ways. Girih star and polygon patterns with 5- and 10-fold rotational symmetry are known to have been made as early as the 13th century. Such figures can be drawn by compass and straightedge. The first girih patterns were made by copying a pattern template on a regular grid; the pattern was drawn with compass and straightedge. Today, artisans using traditional techniques use a pair of dividers to leave an incision mark on a paper sheet that has been left in the sun to make it brittle. Straight lines are drawn with a pencil and an unmarked straightedge. Polygons in contact One of the early Western students of Islamic patterns, Ernest Hanbury Hankin, defined a "geometrical arabesque" as a pattern formed "with the help of construction lines consisting of polygons in contact." He observed that many different combinations of polygons can be used as long as the residual spaces between the polygons are reasonably symmetrical. For example, a grid of octagons in contact has squares (of the same side as the octagons) as the residual spaces. Every octagon is the basis for an 8-point star, as seen at Akbar's tomb in Agra (1605–1613). Hankin considered the "skill of the Arabian artists in discovering suitable combinations of polygons ... almost astounding." Methods of ornamentation were extremely diverse, however, and the idea that one method was used for all of them has been criticised as anachronistic. Two-level design The girih patterns on the Darb-e Imam shrine built in 1453 at Isfahan had a much more complex pattern than any previously seen. The details of the pattern indicate that girih tiles, rather than compass and straightedge, were used for decorating the shrine. The patterns appear aperiodic; within the area on the wall where they are displayed, they do not form a regularly repeating pattern; and they are drawn at two different scales. A large-scale pattern is discernible when the building is viewed from a distance, and a smaller-scale pattern forming part of the larger one can be seen from closer up. The Topkapı Scroll The Topkapı Scroll, from the late 15th century, documents the use of girih tiles to create girih patterns. The drawings in this pattern book show the girih lines superimposed on the tiles used to generate the pattern, making the construction fully evident. Templates Once a repeating pattern has been constructed, regardless of the method used, the pattern can be recreated by copying a repeating unit of it, like the pattern of a wallpaper, as a paper template. The pattern can then simply be pricked through on to the surface to be decorated. The Topkapı Scroll grids may well have been meant for use as such templates. The Anonymous Compendium contains square repeat units for many girih patterns. Ibn al-Razzaz al-Jazari's Compendium of Science and Useful Practice in the Mechanical Arts contains explicit templates for special purposes such as cast bronze doors. ==In varied materials==

File:Salim Chishti Tomb-2.jpg|Girih stone screens at the tomb of Salim Chishti, Fatehpur Sikri, 16th century File:Kayseri Hunat Hatun Complex3-Verity Cridland.jpg|Girih in plasterwork of Iwan of Hunat Hatun Complex, Kayseri File:Flickr - HuTect ShOts - Pattern of The Tomb Gate - Masjid of Sultan Hassan مسجد ومدرسة السلطان حسن - Cairo - Egypt - 28 05 2010.jpg|Girih in metal: 12-pointed star on gate at Sultan Hassan's mosque, Cairo File:Lacería.jpg|Girih in wood: grille in the Great Mosque of Cordoba == Applications ==

On windows Girih has been widely applied in architecture. The patterns on the Persian geometric windows meet the need of the Persian architecture, as the ornateness of windows indicated the social and economic status of the owner. A good example is Azad Koliji, a pavilion in Dowlatabad Garden in Iran. With the girih patterns on its window, the architects manage to demonstrate multiple layers. The first layer is the actual garden which people can see when they open the window. And the second layer is the artificial garden as the girih patterns are on the outside of the window is the carved pattern and a colorful glass is below it which creates an illusion of a beautiful garden. The multi-colour layer create a sense of a mass of flowers. The artificial layer is abstract which forms a clear contradiction with the real layer outside the window and gives the audience enough space of imagination. On domes vault ceiling Girih patterns are widely used on domes. Due to the curve shapes of the domes, they need special techniques. One of the most important techniques is called “Dast-Garden” method. This method refers to that the number of star polygons applied to the pattern are highly dependent on the change of the dome curvature. Decreasing the curvature of a dome surface leads to the decreasing of the number of points on a star polygon. Thus, the shapes of the girih pattern are heavily relying on the dome. On walls Girih patterns are all over the walls of some Islamic architectures. The decorating lines connect to each other and form a continuous network across the entire tiling with edges combine. In addition, girih patterns vary a lot on the surface, with different geometric shapes including decagons, hexagons, bowties and rhombuses. Among all these patterns, a special technique is shared: "self-similar transformation". The mapping is completed by using this freedom to eliminate the edge difference of these patterns and reduce the edge mismatches to the lowest degree. The Girih patterns also have visual function of helping viewers to transcend the monocular vision as the viewers shifting their views according to the underlying schemes. ==See also==