Islamic Greh (Knot) is known as one of the significant geometric patterns in Islamic art and architecture. Because of the complexity of drawing, Greh is considered a prominent and complicated technique and an unknown subject in both artists and orientalist’s points of view. Grehs have been used as decoration in Islamic cultures for over a thousand years, yet have not still lost their attractiveness. Aside from its beauty, many historians and architects are interested in finding the mathematical and geometrical aspects of Greh. Regardless of some old books and documents which introduce the methods of drawing of Greh, many contemporary western researchers have attempted to reinvent their own new methods for drawing Greh. These new methods lead to establish a novel comprehensive insight to understand, draw and use Greh, presenting different results in comparison to traditional methods. The main concern of this paper is to enlighten the differences between traditional and modern methods, based on their applications. These differences could be distinguished well by looking at examples such as those Grehs that are embedded on a curved surface.

In this paper, we provide a comparison between traditional and contemporary methods for drawing Grehs. This comparison reveals that the main feature of traditional method is drawing Grehs according to the geometry of the surface on which they are embedded. This notion is called Chand-Zaminegi in Persian that could be explained by introducing Dast-Gardan Grehs which are impossible to be drawn via modern methods. Unlike common Grehs –which are drawn based on an interactive basic unit- Dast-Gardan is constructed according to the form and shape of the surface, so the measurement and shape of the surface alter the process of its design. Dast-Gardan patterns have been used to materialize the geometric order on a complicated surface like a curved-surface. If Greh is designed and produced by considering Chand-Zaminegi approach, it could be the extension of the traditional method.

This paper consists of six main sections. The first section is an introduction and the second one presents a comprehensive definition of Greh based on documents, books and also lessons taught by some Iranian professional artisans who inherited their profession from their ancestors. The third section introduces the various traditional methods for drawing Greh. This section also describes a sample which shows step-by-step procedures for generating a typical Greh by traditional approaches.  The fourth Section studies modern drawing methods and categorizes all contemporary efforts in seven types. The fifth section is allocated to explain the distinction between traditional and modern methods. For these purposes, some traditional terms like Chand-Zaminegi and Dast-Gardan patterns are introduced. The paper provides a conclusion in section six by explaining the results and suggesting some opportunities for future work